Preheat oven to 350°F, melt 6 TB of butter for sponge cake and set aside for it to cool
Mix almond flour, coconut flour, sweetener, baking soda and salt
In a seprate bowl mix eggs, butter, almond milk, vanilla extract and liquid monk fruit
Combine dry and wet ingredients
Spread half of the batter out in baking dish. Take brown sugar streusal and cover that layer. Then take the remaining batter and spread over the top the best you can, the layers may mix slightly
Spinkle the topping on the bake for 25-30 minutes. Allow to cool then serve.