Preheat the oven to 175C fan and line and grease a 12-hole muffin pan
Blend the beans, zucchini, eggs, milk, maple syrup and vanilla in a blender until smooth
Add the self raising flour and cacao to a large bowl and whisk to combine
Pour the liquid mixture into the dry ingredients and mix until JUST combined
Gently stir in the melted butter and chocolate chips
Divide the mixture between the muffin pan and bake for 25-30 minutes, or until a skewer inserted into the centre of a muffin comes out clean
Store in an airtight container in the fridge for up to five days
