Preheat the oven to 180C/350F. Prepare a 9 x 4 loaf pan with parchment paper and set aside.
In a large mixing bowl, combine your almond flour, coconut flour, baking powder, salt, and cinnamon, and mix well.
In a separate bowl, combine your softened butter and sweetener and whisk together, until combined. Add in the eggs, one at a time, before adding the banana extract and yogurt and whisking it all together, until smooth.
Combine your wet and dry mixture and mix well, until combined. Fold through your chocolate chips and walnuts. Transfer to the lined pan. Cover the pan completely in aluminium tin foil.
Bake the banana bread for 45-50 minutes, removing the tin foil around the 40 minute mark, for the tops to brown. Remove from the oven once the center is mostly set.
Let the bread cool in the pan completely, before slicing.
TO STORE: You must store the bread in the refrigerator, completely covered. It will keep well for up to 2 weeks.TO FREEZE: Leftover slices of banana bread can be stored in the freezer. Place the bread in ziplock bags and keep frozen for up to 6 months. TO REHEAT: To enjoy warm, microwave for 30 seconds, before enjoying it.