Pre-heat oven to 175 degrees. Line 12-tin muffin pan with silicone muffin cups.
Combine the almond flour, oats, baking powder, salt in a large bowl with a wire whisk or spoon.
In another separate medium bowl, add the eggs, mashed bananas, Greek yogurt, maple syrup and vanilla. Combine well by whisking it all up with a wire whisk.
Add the wet ingredients to the bowl with the dry ingredients. Stir to combine well with a spatula. Don't over-mix but stir just until the muffin batter is fully combined and no dry spots are there. Then stir in walnuts.
Divide muffin batter between 10 muffin tins. Bake at 350 degrees F for 23-25 minutes or until an inserted toothpick comes out clean.