Preheat the oven to 175C/350F. Grease and line a 20cm/8 inch square cake tin (or of siilar dimensions)
Place the avocado and maple syrup in a blender/food processer and process until smooth.
Add the eggs, vanilla, coconut flour, baking powder, hazelnut meal and cocoa to the blender and proces until smooth.
Add the chocolate chips and hazelnuts and stir to combine.
Pour the mixture into the cake tin and smooth the top.
Bake in the oven for 30 minutes, or until cooked though.
The Brownie can be served warm or cold. It can be topped with whipped cream and chocolate fudge sauce.