Creamy Broccoli and Cauliflower Gratin with Roasted Cherry Tomatoes

Introduction: A Mediterranean-Inspired Comfort Classic

There’s something undeniably comforting about a bubbling dish of vegetables enrobed in a creamy sauce and topped with a golden, cheesy crust. This Broccoli and Cauliflower Gratin is a Mediterranean-inspired dish that transforms everyday vegetables into a spectacular centerpiece worthy of both weeknight dinners and special occasions.

The combination of tender broccoli and cauliflower florets, sweet cherry tomatoes, and a silky béchamel sauce creates a harmony of flavors and textures that will delight even the most dedicated vegetable skeptics. Rooted in traditional European cooking techniques but updated with contemporary flavors, this gratin has stood the test of time for good reason.

Originally created as a clever way to use seasonal vegetables during colder months, gratins have evolved from humble beginnings to become beloved comfort food classics worldwide. The contrast between the slightly crisp vegetable tops and the tender, sauce-soaked bottoms creates an irresistible eating experience that keeps people coming back for seconds.

Whether you’re looking to incorporate more vegetables into your diet or searching for the perfect vegetarian main dish, this Broccoli and Cauliflower Gratin delivers on all fronts—nutrition, flavor, and visual appeal. Let’s dive into this crowd-pleasing recipe that celebrates the natural beauty and flavor of fresh vegetables.

Ingredients

For the Gratin Base:

900g (2 lbs) broccoli, cut into florets
450g (1 lb) cauliflower, cut into florets
200g (7 oz) cherry tomatoes
1 medium carrot (about 100g/3.5 oz), finely diced
1 bell pepper (about 150g/5.3 oz), diced
1 medium onion (about 150g/5.3 oz), finely chopped
2 garlic cloves, minced
2 tablespoons (30ml) olive oil
Fresh parsley, chopped, for garnish
Salt and freshly ground black pepper to taste

For the Creamy Sauce:

1.2 liters (5 cups) milk
60g (4 tablespoons) unsalted butter
60g (½ cup) all-purpose flour
200g (2 cups) grated cheese (Gruyère, cheddar, or a combination)
¼ teaspoon ground nutmeg
Salt and white pepper to taste

For the Crunchy Topping:

50g (½ cup) breadcrumbs
25g (¼ cup) grated Parmesan cheese
1 tablespoon olive oil
1 teaspoon dried herbs (thyme, oregano, or Italian seasoning)

Instructions

Preparing the Vegetables

Preheat your oven to 190°C (375°F). Lightly grease a large baking dish (approximately 9×13 inches or 23×33 cm).
Prepare the broccoli and cauliflower: Wash thoroughly and cut into medium-sized florets. Remove tough stems but keep some of the tender ones.
Blanch the vegetables: Bring a large pot of salted water to a boil. Add the broccoli florets and cook for 2 minutes. Add the cauliflower and continue cooking for another 2 minutes until both vegetables are bright in color but still firm. Immediately drain and plunge into ice water to stop the cooking process. Once cooled, drain thoroughly.
Prepare the aromatics: Heat the olive oil in a large skillet over medium heat. Add the chopped onion and sauté for 3-4 minutes until translucent. Add the diced carrot and bell pepper, cooking for another 3-4 minutes until slightly softened. Add the minced garlic and cook for 30 seconds until fragrant. Season with salt and pepper. Remove from heat and set aside.

Making the Creamy Sauce

Prepare the béchamel: In a large saucepan, melt the butter over medium heat. Add the flour and whisk continuously for 1-2 minutes to create a roux, being careful not to let it brown.
Add the milk: Gradually pour in the milk while whisking constantly to prevent lumps from forming. Continue cooking and whisking until the sauce thickens enough to coat the back of a spoon, about 5-7 minutes.
Finish the sauce: Remove from heat and stir in three-quarters of the grated cheese until melted and smooth. Add the nutmeg, salt, and white pepper to taste. The sauce should be creamy but pourable – if too thick, add a little more milk.

Assembling and Baking the Gratin

Assemble the gratin: Spread half of the sautéed aromatics in the bottom of the prepared baking dish. Arrange the blanched broccoli and cauliflower on top, distributing them evenly. Scatter the remaining aromatics over the vegetables.
Add the cherry tomatoes: Nestle the whole cherry tomatoes throughout the vegetable mixture.
Pour the sauce: Carefully pour the cheese sauce over the vegetables, ensuring everything is evenly coated. Gently shake the dish to help the sauce settle between the vegetables.
Prepare the topping: In a small bowl, mix together the breadcrumbs, Parmesan cheese, olive oil, and dried herbs. Sprinkle this mixture evenly over the top of the gratin, followed by the remaining grated cheese.
Bake the gratin: Place the baking dish in the preheated oven and bake for 25-30 minutes, until the top is golden brown and bubbling. If needed, broil for the last 2-3 minutes to achieve a perfectly crispy top (watching carefully to prevent burning).
Rest and serve: Remove from the oven and let rest for 10 minutes before serving. Garnish with freshly chopped parsley just before bringing to the table.

Nutritional Information

Per serving (based on 8 servings):

Calories: 320 kcal
Protein: 15g
Carbohydrates: 25g
Dietary Fiber: 6g
Sugars: 8g
Fat: 18g
Saturated Fat: 10g
Cholesterol: 45mg
Sodium: 380mg
Calcium: 35% DV
Iron: 8% DV
Vitamin A: 40% DV
Vitamin C: 120% DV

Timing:

Prep Time: 30 minutes
Cooking Time: 35 minutes
Resting Time: 10 minutes
Total Time: 1 hour 15 minutes

Cooking Tips and Tricks

Perfect Vegetable Texture

Don’t Skip the Blanching: Blanching the vegetables before baking ensures they’ll be perfectly tender in the final dish without becoming mushy.
Ice Bath is Essential: Shocking the vegetables in ice water immediately after blanching preserves their vibrant colors and stops the cooking process.
Dry Thoroughly: Make sure to drain and pat dry the blanched vegetables well. Excess water will dilute your beautiful sauce.

Sauce Secrets

Room Temperature Milk: Using room temperature (or slightly warmed) milk when making the béchamel prevents lumps and helps the sauce thicken more evenly.
Constant Whisking: Never stop whisking when adding milk to your roux. This is the key to a smooth, lump-free sauce.
Cheese Selection Matters: Choose cheeses with good melting properties. A combination of sharp cheddar for flavor and Gruyère for meltability creates the perfect balance.
Freshly Grated is Best: Pre-shredded cheeses often contain anti-caking agents that can affect the smoothness of your sauce. Grating your own cheese results in a silkier texture.

Baking Brilliance

Right Baking Dish: Use a shallow baking dish rather than a deep one. This provides more surface area for that coveted golden crust.
Rotate for Even Browning: Halfway through baking, rotate your dish for even browning, especially if your oven has hot spots.
Rest Before Serving: Allowing the gratin to rest for 10 minutes helps the sauce set slightly, making it easier to serve neat portions.

Flavor Boosters

Roast Some Tomatoes Separately: For an extra flavor dimension, roast half the cherry tomatoes separately with olive oil, salt, and balsamic vinegar until they burst, then add them to the top of the gratin during the last 10 minutes of baking.
Herb Infusion: Infuse your milk with herbs (bay leaf, thyme sprigs) and a halved garlic clove while warming it. Strain before using for a subtle flavor enhancement.
Mustard Magic: A tablespoon of Dijon mustard added to the béchamel brings a pleasant tang that complements the rich cheese perfectly.

Variations and Substitutions

Dietary Adaptations

Gluten-Free Option: Substitute the all-purpose flour with a gluten-free flour blend or cornstarch slurry (2 tablespoons cornstarch mixed with cold milk) for the béchamel. Use gluten-free breadcrumbs for the topping.
Dairy-Free Alternative: Replace the milk with unsweetened almond, oat, or soy milk. Use dairy-free cheese alternatives and nutritional yeast for a cheesy flavor. Coconut oil or vegan butter can replace the butter in the roux.
Lower-Calorie Version: Use 2% or skim milk instead of whole milk, reduce the cheese by half, and substitute half the béchamel with puréed cauliflower for creaminess with fewer calories.

Vegetable Variations

Green Veggie Gratin: Substitute half the vegetables with green beans, asparagus, or Brussels sprouts for a different flavor profile.
Root Vegetable Addition: Include diced parsnips, turnips, or sweet potatoes for a heartier, winter-appropriate version.
Mediterranean Twist: Add artichoke hearts, sundried tomatoes, and black olives for a Mediterranean-inspired variation.

Flavor Modifications

Spicy Kick: Add a pinch of cayenne pepper or red pepper flakes to the sauce, or incorporate diced jalapeños into the vegetable mix.
Smoky Sensation: Add a teaspoon of smoked paprika to the sauce or use smoked cheese for a portion of the cheese component.
Herb Garden: Incorporate fresh herbs like thyme, rosemary, or sage into both the sauce and the vegetable mixture for an aromatic version.

Meal Adaptations

Protein-Packed: Add cooked, diced chicken, ham, or crispy bacon between the vegetable layers. For a vegetarian protein boost, mix in white beans or chickpeas.
Seafood Special: Incorporate flaked cooked salmon or shrimp for an elegant seafood gratin.
Complete Meal: Mix in cooked quinoa, farro, or brown rice to transform the gratin into a complete one-dish meal.

Common FAQs

1. Can I prepare this gratin ahead of time?

Answer: Absolutely! You can prepare the gratin up to the point of baking and refrigerate it, covered, for up to 24 hours. When ready to serve, remove from the refrigerator 30 minutes before baking to take the chill off, then bake as directed, adding an extra 5-10 minutes to the cooking time if needed.

2. Why is my gratin watery?

Answer: A watery gratin typically results from not drying the blanched vegetables thoroughly or using vegetables with high water content without preparing them properly. Be sure to drain blanched vegetables well and pat them dry. For vegetables like tomatoes, you can salt them lightly and let them sit for 10 minutes to draw out excess moisture before incorporating them into the dish.

3. Can I freeze leftovers?

Answer: While you can freeze leftovers, the texture of the sauce may change slightly upon thawing and reheating. To freeze, cool the gratin completely, portion it, and store in airtight containers for up to 2 months. Thaw overnight in the refrigerator and reheat in a 350°F/175°C oven until hot throughout, about 20-25 minutes. Cover with foil if the top starts to brown too much.

4. How can I make the top extra crispy?

Answer: For an extra-crispy top, mix a tablespoon of melted butter with your breadcrumb mixture and make sure to use panko breadcrumbs rather than regular ones. Additionally, finish the gratin under the broiler for 2-3 minutes (watching carefully) after it’s fully baked to achieve that perfect golden crust.

5. What can I serve with this gratin?

Answer: This versatile gratin works beautifully as a vegetarian main dish served with a simple green salad and crusty bread. As a side dish, it pairs wonderfully with roasted chicken, grilled fish, or a simple steak. For a lighter meal, serve smaller portions alongside a bowl of soup.

Storage and Make-Ahead Tips

Refrigerating Leftovers

Proper Cooling: Allow the gratin to cool completely before refrigerating (no more than 2 hours at room temperature).
Storage Container: Transfer leftovers to an airtight container or cover the baking dish tightly with plastic wrap or aluminum foil.
Refrigeration Time: Properly stored, the gratin will last 3-4 days in the refrigerator.
Reheating Method: For best results, reheat individual portions in the microwave for 1-2 minutes or until heated through. To reheat the entire gratin, cover with foil and bake at 350°F/175°C for 15-20 minutes until hot, removing the foil for the last 5 minutes to re-crisp the top.

Freezing Instructions

Freezing Method: For best results, freeze the gratin before baking. Assemble completely, cool thoroughly, cover tightly with plastic wrap and then aluminum foil, and freeze for up to 2 months.
Freeze in Portions: Consider freezing in individual portions for easier thawing and reheating.
Thawing Process: Thaw overnight in the refrigerator before baking according to the original instructions, adding 10-15 minutes to the baking time.
Freezing Baked Gratin: If freezing already-baked leftovers, know that the texture may change slightly, though the flavor will remain good. Reheat covered at 350°F/175°C until heated through.

Make-Ahead Strategies

Day Before Prep: Blanch and dry the vegetables, prepare the cheese sauce, and store them separately in the refrigerator. Assemble and bake the next day.
Partial Assembly: Assemble the vegetables and aromatics in the baking dish, cover, and refrigerate. Prepare the sauce and topping separately, then combine and bake when ready to serve.
Complete Assembly: Assemble the entire dish up to the point of baking, cover tightly, and refrigerate for up to 24 hours. Let sit at room temperature for 30 minutes before baking.
Component Prep: Several components can be prepared up to 3 days in advance:
Blanched vegetables (stored in an airtight container)
Cheese sauce (reheat gently, whisking to recombine before using)
Breadcrumb topping (store in an airtight container at room temperature)

With these make-ahead options, you can easily incorporate this impressive gratin into meal plans for busy weeknights or elaborate dinner parties with minimal day-of preparation.

This Broccoli and Cauliflower Gratin celebrates the natural goodness of vegetables while transforming them into something truly special. The combination of creamy sauce, tender vegetables, and crispy topping creates a dish that appeals to all the senses. Whether served as a comforting main dish or an elegant side, this versatile gratin is sure to become a regular feature on your table throughout the seasons.