Preheat your oven to 375 degree and grease your doughnut pan.
In a small bowl combine your almond flour, coconut flour, baking soda, baking power, salt and psyllium husk powder.
In a large bowl whisk together your coconut oil, monk fruit sugar, eggs, acv and vanilla.
Add the dry mixture to the wet and combine, then add in your bananas and sour cream and mix until fully incorporated.
Fill your doughnut pan with the batter, for ease I like to pipe the batter in using a pastry bag or Ziploc with the tip snipped.
Melt your tablespoon of butter in a small dish and add the cinnamon to the sugar in a large bowl.
Bake the doughnuts for 12-15 minutes or until a toothpick comes out clean. Allow doughnuts to rest for 3-5 mins then carefully remove from pan and use a pastry brush to butter the tops of the doughnuts and roll in the cinnamon and sugar mixture.