Preheat your oven to 350 degrees F. Grease an 8x8-inch baking dish with a little bit of butter or cooking spray.
In a large mixing bowl, whisk together the peanut butter, maple syrup, milk, eggs, vanilla extract, and mashed banana until smooth.
In another bowl, mix the oats, cocoa powder, chocolate protein powder, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, stirring until well combined.
Fold in the chocolate chips, saving a few to sprinkle on top if you like.
Pour the mixture into the prepared baking dish. Spread it out evenly and sprinkle any reserved chocolate chips on top.
Bake for 30-35 minutes, or until the top is set and slightly golden. A toothpick inserted into the center should come out clean.
Let it cool for a few minutes before cutting into squares. Serve warm, and if you’re feeling extra indulgent, add an extra drizzle of peanut butter on top.