In a saucepan, melt the butter and cacao butter over medium heat.
Stir in erythritol and cocoa powder, mixing until well combined.
Stir in peanut butter and cook for 1-2 minutes, or until mixture is homogeneous.
Remove from heat and stir in coconut flakes.
Drop even spoonfuls of mixture onto a plate or cookie sheet and place in freezer.
Freeze for 15-20 minutes or until cookies are firm.
Note: Store in the fridge.