#1. Cook pasta according to package instructions, set aside.#2. Prepare the sauce by melting butter over med-low heat, in a large saucepan. Whisk in flour and cook for 2-3 minutes.#3. While whisking, slowly add the milk and bring to a simmer , stirring often until the sauce begins to thicken (careful not to boil sauce).#4. Add the dry mustard, Worcestershire sauce, and a generous amount of salt and pepper. Remove from heat.#5. Slowly add the Mifroma® Gruyere cheese and the Parmesan. Whisk until completely melted. Fold in pasta shells and mix well. Add bacon, add more salt and pepper, to taste.