01 - Preheat the oven to 350°F. Lightly grease a 9x9 inch baking dish with cooking spray or a small amount of oil.
02 - In a large bowl, whisk together the mashed bananas, eggs, Greek yogurt, honey, almond milk, and vanilla extract until the mixture is smooth and fully incorporated.
03 - In a separate medium bowl, combine the rolled oats, protein powder, baking powder, cinnamon, and salt. Stir well to evenly distribute the leavening agent and spices.
04 - Add the dry ingredients to the wet mixture and stir until just combined. Be careful not to overmix, as this can affect the texture of the final bake.
05 - Gently fold in the blueberries using a spatula, taking care to avoid crushing the fruit.
06 - Pour the batter into the prepared baking dish, spreading it evenly. Sprinkle chopped walnuts or almonds and chia seeds on top if using.
07 - Bake for 35 to 40 minutes, or until the top is golden brown and a toothpick inserted in the center comes out mostly clean.
08 - Allow the breakfast bake to cool for 10 minutes before slicing. Serve warm or at room temperature.