Macaroni au Gratin recipe | Delia Smith

Ingredients

• 4 oz (110 g) any supermarket macaroni
• 2 oz (50 g) mushrooms, sliced
• 1 tomato, cut into small pieces
• Salt and freshly milled black pepper
• 2 oz (50 g) butter
• A little extra butter
• 11/2 oz (40 g) plain flour
• 1 level teaspoon mustard powder
• ¾ pint (450 ml) milk
• 6 oz (175 g) Cheddar cheese, grated
• A little freshly grated nutmeg
• 1 medium onion, peeled and chopped
• 4 rashers streaky bacon, rinded and chopped