Preheat the oven to 180C/350F degrees
Grease and line a 8 inch baking pan with parchment paper.
In a bowl, cream the butter and erythritol together until smooth.
Add the eggs, one at a time, into the batter
Then add the vanilla extract and coconut milk and beat until smooth.
Next, add the coconut flour, baking powder and salt. Stir until smooth.
If the mixture is a bit too thick, add more coconut milk (coconut flour can vary between brands).
Spoon the blondie mixture into the baking tin and spread evenly.
For the cinnamon swirl, mix the butter, cinnamon and powdered erythritol in a small bowl.
Spoon the cinnamon mixture on top of the blondie mixture and give it a light swirl, gently mixing it into the batter.
Bake for 25-30 minutes until firm and golden.
Allow to cool in the tin for at least 30 minutes.