Preheat oven to 350°F and line a 9x9 inch baking dish with parchment paper.
In a large bowl combine rolled oats, quinoa, baking powder, cinnamon and salt.
In a separate bowl mix bananas, egg, flax, chia seeds, nut butter, maple syrup, and vanilla extract. Stir until well-combined.
Fold the wet ingredients into the dry ingredients and mix in any optional add-ins.
Add batter to baking dish and spread into an even layer using a silicone spatula.
Bake for 25 mins or until edges are crisp and center is cooked through and firm.
Let cool for 10 minutes before transferring to a cooling rack to cool completely.
Cut 9-12 bars or squares and enjoy!
Store in an airtight container in the refrigerator for up to 1 week or freeze for up to 2 months.