6 tbsp. butter
1 cup panko breadcrumbs
1 cup shredded Gruyère or Parmigiano-Reggiano
¼ cup flat-leaf parsley leaves, chopped
12 oz. extra-wide egg noodles
⅓ cup (a handful) fresh dill sprigs, finely chopped
2 tbsp. olive oil
12 oz. white mushrooms, sliced or chopped
1 large shallot, finely chopped
3 large cloves garlic, chopped
Finely ground black and white pepper
2 tbsp. flour
½ cup dry sherry, dry (white) vermouth, or white wine
2 cups whole milk
Freshly grated nutmeg (about 1/8 tsp.)
3 to 4 cups shredded or chopped cooked turkey or rotisserie chicken
½ cup (a generous handful) fresh or frozen peas
Bring a large pot of water to a boil for the noodles.
In a small saucepan, melt 4 tbsp. butter over low heat. Mix in the panko, cheese, and parsley.
Arrange a rack in the center of the oven. Preheat the broiler.
Salt the boiling water and add the noodles. Cook until 1 minute shy of the package directions. Drain; return to the pot. Toss with the dill and 1 tbsp. butter.
Meanwhile, in a large skillet, heat the oil, two turns of the pan, over medium. Add the remaining 1 tbsp. butter. When it melts, add the mushrooms; cook, stirring often, until lightly browned. Add the shallot and garlic; season with salt, black pepper, and white pepper. Sprinkle with the flour. Add the sherry; cook, stirring often, until absorbed, about 1 minute. Add the milk; season with nutmeg. Cook until the sauce thickens slightly, about 3 minutes. Add the turkey and peas; cook, stirring often, until heated through, about 4 minutes.
Mix the sauce into the noodles. Transfer to a large baking dish. Top with the breadcrumbs. Broil until the top is browned and the edges are bubbling, 3 to 4 minutes.