Preheat the oven to 350 degrees F, properly grease 2 cake pan with cooking spray then line them with baking paper, set aside. With a bowl, mix the milk and vinegar then let sit for about five minutes. In another mixing bowl, add the flours, cocoa powder, espresso powder, sweetener, baking powder, baking soda, and salt to taste then mix everything properly to combine.
In another bowl, add in the oil, eggs, and vanilla then mix properly to combine. Pour the egg mixture into the flour then mix again to combine. Pour the cake batter into the prepared cake pans, place the pans into the preheated oven, and bake the cakes for about eighteen to twenty-five minutes. Let the cake cool for about thirty minutes
For the frosting, beat the butter with a hand mixer until it becomes fluffy. Add in the rest of the ingredients and beat again until fully combined. Frost the cake as desired, slice with a knife, and serve.
Calories 176, Fat 16g, Carbohydrates 7g, Fiber 3g, and Protein 5g.