Preheat the oven to 180C/350F degrees.
Mix the dry brownie ingredients in a bowl.
Grease and line a square brownie tin with parchment paper.
In another bowl, mix the eggs and sugar substitute and blend well.
Add the butter and coconut milk and combine until smooth.
Add the dry ingredients to the wet mixture and whisk until smooth. (I use a hand whisk).
Place the topping ingredients in a bowl and using a hand blender mix until smooth. You could also use a blender for this.
Spoon the brownie mixture into the brownie tin and smooth over evenly with a spoon.
Dollop the peanut butter mixture on top of the brownie mixture and gently mix it slightly in.
Bake for 35-40 minutes until firm.