Make a cheese sauce by melting the spread in a pot and adding flour and mustard powder to make a roux. Gradually add soya milk whilst continuously stirring to create a smooth thick sauce which coats the back of a spoon. Allow to cook out for 10 minutes, add cheese to taste. Cook macaroni as per manufacturer’s instructions. In a separate pan fry the leeks with garlic and add the spinach. Stir the veg and pasta into cheese sauce and mix thoroughly. Transfer to oven proof dish and top with breadcrumb and cheese substitute. Bake in a hot oven until the crumb turns golden.