• In a small bowl, use a fork and mash the ripe banana until smooth and mushy.
• Stir in quick oats, protein powder, and any additional ingredients like vanilla, cinnamon, or chocolate chips.
• Stir until the dough is coming together into a bowl. It should be wet but not liquid. Add more protein powder, 1 teaspoon at a time, to firm up the dough or more mashed banana (or 1-2 teaspoons of water) if too dry.
• Line a baking sheet or bottom of the air fryer basket with a piece of lightly oiled parchment paper.
• Press down the dough into a large 7-inch cookie (18 cm).
• Bake the cookie in an oven preheated to 350°F (180°C) or air fryer for 12 to 15 minutes or until the top and sides are golden brown.
• Cool down on a wire rack for 5 minutes to steam out. The cookie will be soft and chewy not crispy.

Storage

• Store in the fridge for up to 2 days in an airtight container or freeze up to 3 months and thaw at room temperature the day before.