Preheat the Oven: Set your oven to 180°C (356°F) and lightly grease your baking dish or line it with parchment paper to prevent sticking.

Make the Batter: In a mixing bowl, whisk together the eggs and sugar until light and slightly frothy. Add the melted butter and mix well. Gradually sift in the flour and baking powder, stirring until a smooth batter forms. It should have a slightly thick, pourable consistency.

Prepare the Base: Pour the batter into the greased baking dish and spread it evenly across the surface. This will be the base layer that holds the filling.

Prepare the Cottage Cheese Mixture: In another bowl, combine the cottage cheese, eggs, sugar (or sweetener), vanilla extract, and melted butter. Mix until smooth. You can use a hand blender for a creamier texture if you prefer a silky filling.

Assemble the Cake: Pour the cottage cheese mixture evenly over the base batter. Arrange the sliced apple on top in a circular pattern or scatter them randomly for a rustic look. Sprinkle the blueberries evenly across the top. The berries will sink slightly as the cake bakes, creating juicy pockets of flavor.

Bake: Place the dish in the preheated oven and bake for 40–50 minutes, or until the top is lightly golden and a toothpick inserted into the center comes out clean. The cake should be set in the middle and slightly puffed up.

Cool and Serve: Let the cake cool for about 15 minutes before dusting with powdered sugar. Serve warm, or let it chill completely for a firmer texture.