8 tablespoons unsalted butter
1 leek, julienned
3 tablespoons all-purpose flour
2½ cups whole milk
½ pound white cheddar cheese, shredded
1 pound leek and morel cheese, shredded
1 tablespoon Dijon mustard
¼ teaspoon ground nutmeg
¼ teaspoon cayenne pepper
Kosher salt and ground pepper
1 pound macaroni, cooked according to box instructions
1 cups Panko breadcrumbs
Preheat the oven to 350°F.
Heat a 5 quart stockpot over medium-high heat. Melt 4 tablespoons butter. Add leeks and sauté until soft. Add flour and cook for 3 minutes. Reduce heat to medium and add milk, ½ cup at a time, cooking until thick, whisking constantly. Add cheeses in installments stirring until melted then proceeding until all cheese has been added. Stir in mustard, nutmeg and cayenne pepper. Season cheese mixture with salt and pepper to taste. Add noodles and fold until well coated.
In a glass bowl melt remaining butter. Add bread crumbs and mix well.
Pour macaroni into a casserole dish and top with bread crumbs. Place in oven until bread crumbs are lightly browned. Remove from oven and rest for 5 minutes before serving.