01 - Preheat the oven to 350°F. Lightly grease a 9x9 inch baking dish with cooking spray or butter.
02 - In a large bowl, whisk together the mashed bananas, eggs, Greek yogurt, honey, almond milk, and vanilla extract until completely smooth and well incorporated.
03 - In a separate medium bowl, combine the rolled oats, protein powder, baking powder, cinnamon, and salt. Whisk to ensure even distribution of leavening agents and spices.
04 - Pour the dry ingredients into the wet mixture. Stir gently with a spatula until just combined, being careful not to overmix as this can affect the final texture.
05 - Gently fold in the blueberries using a spatula, taking care to distribute them evenly without crushing the fruit.
06 - Pour the batter into the prepared 9x9 inch baking dish, spreading it evenly with the spatula. Sprinkle chopped nuts and chia seeds over the top if desired.
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 with moist crumbs attached.
08 - Allow the breakfast bake to cool in the pan for 10 minutes before slicing into squares. Serve warm or at room temperature.