Melt butter and set aside.
Warm the coconut milk and dissolve the matcha powder in it and set aside.
Beat the eggs
Add the vanilla essence and erythritol to the egg mixture and beat.
Pour the melted butter into the egg mixture and mix well.
Add the sour cream into the mixture and mix well.
Mix the dry ingredients together (almond flour, okara flour, baking powder, salt) and add into the cake mixture. Mix well.
Set aside 20% of the cake mixture and mix with the matcha.
Pour in the matcha mixture as the middle layer.
Pour in the last 1/4 of the cake mixture as the top layer.
Use a thin stick (eg. skewer / satay stick) to make swirling patterns.
Bake at 175 degrees celsius for 50-55 minutes.
Serving Suggestion: Shave some keto white chocolate and sprinkle on top.