1 pound elbow pasta, cooked
6 tablespoons unsalted butter plus more for dish
2 cups panko flakes
2 pounds sharp cheddar, grated (about 7 cups)
4 tablespoons all-purpose flour
1 teaspoon red pepper flakes
1 teaspoon black pepper
2 teaspoons salt
3 cups 2% milk
2 cups heavy cream
8 ounces gruyere, grated (about 2 cups)
1 tablespoon Dijon mustard

1. Preheat oven to 400 degrees, butter a large baking dish and grate cheese while pasta is cooking.
2. In a large saucepan over medium heat, melt 2 tablespoons of butter and integrate panko and one cup of cheddar. Remove from pan and set aside.
3. Return pan to heat and melt remaining butter.
4. Add flour and stir constantly over medium heat for three minutes. Season with red pepper flakes, salt and pepper.
5. Whisk in milk, bring sauce to a boil, whisking constantly, reduce heat to medium-low and simmer for 5 minutes to thicken.
6. Stir in cream, cheese and mustard until sauce is a uniform consistency. Remove from heat.
7. Stir cooked pasta into the sauce and pour into the buttered baking dish.
8. Spread breadcrumb mixture across the top and bake 25 minutes or until golden brown on top and bubbly throughout.