Prepare 12 paper muffin cases in muffin tin Mix together the self-raising and plain flour, baking powder, bicarbonate of soda, salt and mustard powder in a bowl. In a separate bowl, mix the cheese, oil, yogurt, milk, egg and Worcestershire sauce. Combine all the ingredients and divide between the muffin cases in the muffin tin. Place in the oven for 20-25 mins until golden. Remove and cool slightly on a rack.