Prep the pan and oven: Heat oven to 350°F (175°C). Grease an 8x8-inch baking dish with butter or oil.
Cook the apples: Core and slice apples thinly. In a skillet, warm a little butter over medium heat.
Add apples, 1 teaspoon cinnamon, a pinch of salt, and a drizzle of maple syrup. Sauté 4–5 minutes until just tender. Optional: add a squeeze of lemon.
Blend the base: In a blender, combine cottage cheese, eggs, remaining maple syrup, vanilla, baking powder, remaining cinnamon, nutmeg, and oats.
Blend until smooth and creamy.
Layer it up: Spread the sautéed apples evenly in the baking dish. Sprinkle raisins or walnuts if using. Pour the cottage cheese mixture over the top and gently shake the pan to level.
Bake: Place on the center rack and bake 30–40 minutes, until the edges are set and the center barely jiggles.
A knife inserted near the center should come out mostly clean.
Rest and serve: Let it cool 10–15 minutes to finish setting. Slice into squares. Serve warm as is, or top with a dollop of Greek yogurt and a drizzle of maple syrup.