Preheat the oven to 220°C fan and line a 12-hole muffin tin with 6 muffin liners, leaving every other hole free (this will help the muffins rise extra tall).
In a large bowl, whisk the 160 grams self-raising flour, 30 grams Menier 100% Cocoa Powder, 0.5 teaspoon baking powder, 150 grams caster sugar and 0.5 teaspoon salt together.
In a separate bowl or jug, whisk the 1 medium egg, 75 mililitres milk, 75 grams sour cream and 50 mililitres vegetable oil together.
Pour the wet ingredients into the dry ingredients and fold together until the mixture is just combined. Be careful not to overmix - you're looking for a lumpy mixture with lots of air bubbles.
Chop up the 100 grams Menier Milk Chocolate and fold into the mixture. Set the bowl aside while you make the cheesecake filling.