Preheat your oven to 200 degrees and line a 12 hole muffin tin with paper cases.
Cut the butter into cubes and place into a microwave safe bowl and cook for 20 second spurts until melted. set aside to cool slightly.
Place the self raising flour, baking powder and brown sugar into a large bowl and stir to combine.
Add the milk, egg, milo, chocolate chips and melted butter to the bowl with the dry ingredients and gently stir until just combined.
Divide the mixture between the paper cases and fill until approximately ⅔ full.
Place the Chocolate Chip and Milo Muffins into the oven to cook for 18 - 20 minutes or until cooked through when tested with a skewer.
Remove the muffins from the oven and let them cool in the tin for 5 minutes before carefully transferring to a wire rack to cool completely.