Heat oven to 350 degrees
Lightly grease six mini bundt pans (or use a jumbo muffin tin)
Add bananas, eggs, peanut butter, butter, vanilla, and lemon juice to a large mixing bowl
Mix at medium speed for a minute or two to combine and mash bananas
Add coconut flour, almond flour, baking soda, cinnamon, and salt to the bowl and mix until combined
Add batter to bundt cake pans so they are about 2/3 full
Bake for 25 - 30 minutes until toothpick inserted in the deepest part of cake comes ouut clean
Cool on wire rack for 15 - 30 minutes
To remove from bundt pans - use a butter knife and gently insert between the cake and the pan lightly move the knife around the cake to loosen it from the pan. Turn the pan over and lightly tap the bottom with the knife. Use the knife to help dislodge from the pan if needed.
If you don't have mini bundt pans you can use a jumbo muffin pans and jumbo muffin liners instead of oiling the pan.
If you use a standard size muffin pan - decrease the cooking time 5 - 10 minutes.