Preheat your oven to 350°F (180°C). Line a 7x7 inch (15x15 cm) baking pan with parchment paper or lightly grease it with oil.
To a high-speed blender or food processor, add egg, ripe bananas, cottage cheese, and rolled oats. For extra flavor, include a splash of lemon juice, vanilla extract, and a bit of maple syrup.
Blend on high speed until completely smooth. Your oats should turn into flour and the batter should be lump-free.
Rinse the blueberries. To keep them from sinking, toss them with ½ tablespoon of flour in a bowl (optional, but helpful). Stir the blueberries into the blended batter gently. Do not blend again.
Pour the batter into the prepared baking pan, spread evenly, and optionally top with more blueberries for extra flavor and color.
Bake for 30–35 minutes, or until the center is set and a toothpick comes out clean. The edges should look golden and slightly crisp.
Let the bake cool in the pan for at least 30 minutes before slicing. This helps it set and makes it easier to cut clean squares.