Prep the oven and pan.
Heat your oven to 350°F (180°C). Line an 8-inch (20 cm) round pan with parchment paper (or grease it well). Parchment is the easiest way to get clean slices out later.

Prepare the peaches.
Wash the peaches. Pit both. Roughly chop 1 peach for the batter. Slice the second peach thinly for the top (about 1/8-inch / 3 mm thick slices).

Blend the batter until smooth.
In a blender, add:
2 cups (180 g) rolled oats, the chopped peach, 2 eggs, 3/4 cup (180 g) yogurt, 1/3 cup (85 g) almond butter, 1/4 cup (60 ml) maple syrup, 1 1/2 tsp baking powder, and 1 tsp vanilla.
Blend until the batter looks mostly smooth and creamy, scraping down once if needed. It should pour like a thick smoothie.

Rest briefly (quick but helpful).
Let the batter sit in the blender (or a bowl) for 3–5 minutes. This gives the oats a moment to hydrate and helps the cake bake up more evenly.

Fill the pan and top with peach slices.
Pour the batter into the prepared pan and smooth the top. Arrange the sliced peach over the batter (overlapping is nice). Gently press the slices in just a little so they adhere.

Bake.
Bake for 35–40 minutes, until the cake is set, lightly golden at the edges, and the center springs back when you gently press it. A toothpick should come out mostly clean (a few moist crumbs are fine; wet batter is not).

Cool before slicing.
Cool in the pan for 15 minutes, then slice. For the cleanest slices, cool closer to 30 minutes—the custardy crumb firms up as it rests.