01 - Preheat your oven to 350°F. Lightly grease an 8x8-inch baking dish with cooking spray or a small amount of oil.
02 - In a large mixing bowl, whisk together Greek yogurt, eggs, almond milk, maple syrup, lemon juice, lemon zest, and vanilla extract until the mixture is completely smooth and well blended.
03 - Add the rolled oats, protein powder, baking powder, and salt to the wet mixture. Stir gently until just combined, being careful not to overmix.
04 - Gently fold the blueberries into the batter, taking care to avoid crushing them.
05 - Pour the mixture into the prepared baking dish and smooth the top with a spatula. If desired, sprinkle sliced almonds and chia seeds evenly over the surface.
06 - Bake for 35 minutes, or until the center is completely set and the top is golden brown. A toothpick inserted in the center should come out clean.
07 - Let the breakfast bake cool for 5 to 10 minutes before slicing into squares. Serve warm or at room temperature.