Preheat the oven to 200C/180C Fan/Gas 6. Line a 6 hole muffin tin.
In a large bowl, combine the flour, baking powder, sugar and cocoa powder.
Add in the milk, egg, melted butter (ensure it's not still piping hot) and vegetable oil. Stir together with a wooden spoon until just combined.
Add in the chocolate chips/chunks. Spoon the batter into the lined muffin tin and bake for 18-20 minutes - until the tops are a dark brown and a skewer inserted comes out clean. Let cool on a wire rack before eating (although so great eaten warm!).