Preheat oven to 350 degrees F.
Mix almond flour, coconut flour, baking powder and sweetener.
In separate bowl, beat eggs and then blend in heavy cream, sour cream, milk, vanilla and butter. Blend well.
Add wet to dry and whisk until there are no lumps.
Scoop into cupcake liners or lined cake pans (lined with parchment paper). I used a large ice cream scoop (1/4 cup) for cupcakes.
Bake cupcakes for 15 minutes and check. Will possibly need up to another 5 minutes.
Bake 8'' cakes for about 22-25 minutes and check for doneness.
Carefully remove from pan and remove paper and cool on rack.
**Note: If batter is a little thick, simply add a few more tablespoons of dairy. I always weigh my ingredients on a scale because the volume of flour will vary depending if the flour is packed or not and this can affect how much liquid you need.
** Update: To an even lighter cake, separate the egg whites and yolks. Beat the egg whites until soft peaks form and blend the egg yolks with the other wet ingredients. Blend dry ingredients with wet and then fold egg whites into batter.