Liberally coat an 8-inch square baking dish with oil spray and set aside. Preheat oven to 350 degrees.

In a mixing bowl, mash the banana and stir in the peanut butter until smooth, but it’s okay to have lumps of banana throughout. Add in the egg. Stir in the chocolate protein powder and cocoa powder, and blend until the ingredients are well-combined and creamy.

Add batter to the prepared baking dish, smooth with a spatula or spoon to evenly distribute, and tap on counter a few times to set. Bake in the oven on middle rack for about 25 minutes. Remove and let cool on counter for at least 10 minutes. Slice into 9 squares and enjoy!

Store in an airtight container on the counter for 3 to 4 days or in the fridge for up to a week. You can also freeze them: Wrap individual brownies in plastic wrap and a second layer of foil. Place in an airtight container or zip-top bag. When you’re ready to enjoy one, allow brownie to defrost on a plate at room temp or microwave for 10 to 15 seconds on low.