Preheat oven to 350°F (175°C) and line a loaf pan with parchment paper.
In a large bowl, mash bananas. Add eggs, almond butter, yogurt, and vanilla. Stir until combined.
Add almond flour, oat flour, protein powder, baking soda, cinnamon, and salt. Mix until smooth.
Fold in optional walnuts or chocolate chips.
Pour batter into prepared pan and spread evenly.
Bake 40–45 minutes or until a toothpick comes out clean.
Let cool in pan 10 minutes, then transfer to wire rack.
Slice and enjoy. Store leftovers in an airtight container.