Preheat the oven to 180°C / Fan 160°C.
Line a 20×20cm tin with baking paper or just grease it.
Place all the ingredients except the chocolate chips in a food processor and blend till smooth.
Alternatively, mix all ingredients in a bowl except the choc chips and blend well using a hand blender.
Stir in most of the chocolate chips, saving a few for the decoration.
Pour the mixture into the prepared tin.
Smooth the surface with the back of a spoon and press the remaining chocolate chips on top.
Bake for 18-20 minutes until risen and slightly firm.
Leave to cool in the tin (it will firm up as it cools).