Pre-heat the oven to 180C (160C fan or gas mark 4). Now mix the sugar, flour, cocoa and baking powder in a large bowl. Whisk together the eggs, Mr Hugh’s Hazelnut Baking Oil and milk in a separate bowl and then stir into the dry ingredients until well combined. Then stir in the milk chocolate chips.
Place cupcake cases into a 12-hole tin. Divide the mixture evenly between the cases and then bake for 20 minutes until risen and cooked through. Leave to cool for 5 minutes then remove from the tin onto a baking tray to cool completely.
Just before serving, heat the grill to a medium temperature, arrange the marshmallows on the top of the cakes, (if they won’t stay use a little runny honey to help them stick) and pop them under the grill for 30 seconds, keeping a close eye as they won’t need long to just brown the top of the marshmallows. Remove and serve immediately.