Step 1: Put the pasta on boil with salted water.
Step 3: Melt the butter on a medium heat (I use 4 on an electric hob). As soon as the butter has melted, stir in the flour. Cook the flour for a minute then add the milk in small amounts. Add the mustard.
Step 5: Once all of the milk is added, whisk continuously until it reaches the consistency you want. Season as you go along, tasting to make sure it is to your taste.
Step 7: Add most of the cheese and melt off the hob (don’t use all of the cheese because you want some to go on top)
Step 9: Stir the pasta into the sauce and pour into an oven dish. Put the rest of the cheese in and place in the oven for 5 minutes.
Step 11: Serve with garlic bread and salad or by itself.
Step 13: (A great alternative is with peas and ham, just stir in once the milk has all been added)