4oz grated Emmental Cheese
4oz grated Gruyere Cheese
1Tbs Dijon Mustard
1Tbs Worcestershire Sauce
1/2tsp dried Thyme
Black Pepper to taste
3oz grated Parmigiano-Reggiano Cheese
Boil pasta in a cast iron skillet. Melt the butter and whisk in flour until well combined. Whisk milk into the flour mixture. Whisk constantly until thickened 1 to 2 minutes.
Add Emmental Cheese, Gruyere, mustard, Worcestershire, and thyme. Whisk until melted and smooth, about 2 minutes. Stir in pasta and season to taste with salt and pepper.
Sprinkle Parmigiano-Reggiano on top and broil until browned.