Chicken and Mushroom Pasta Bake

Set the oven to 350°F and lightly coat a large rectangular baking dish or lasagna pan with grease. Boil a large pot of heavily salted water.

In a large Dutch oven or heavy pot, melt 2 tablespoons of butter over medium-high heat. Add mushrooms and cook until they release liquid, about 4 minutes. Add onion, garlic, and a pinch of salt, stirring often, until onions are clear, about 8 minutes. Add water and bring to a boil; continue cooking until most liquid evaporates. Move the mushroom mixture to a separate bowl with the shredded chicken.

To prepare the bechamel sauce, melt the remaining 4 tablespoons of butter in the pot over medium heat. Stir in flour until a thick paste forms; cook for about 1 minute to remove the raw taste. Pour in milk and chicken stock, whisking often until thickened, 10 to 15 minutes. Whisk in salt, mustard powder, and a generous amount of freshly ground black pepper, followed by 1/4 cup grated Parmesan.

While the bechamel thickens, cook the noodles. Add them to the boiling water and cook, stirring occasionally, until al dente, 7 to 8 minutes. Drain and place on a lightly greased sheet pan to prevent sticking.

Mix the chicken and mushroom mixture into the bechamel. Taste and adjust seasoning, being generous with salt and pepper. In a separate bowl, mix mozzarella, Gruyere, and the remaining 3/4 cup Parmesan cheese. Spread 1 cup of the chicken mixture at the bottom of the prepared baking dish. Place 4 noodles on top, overlapping if needed. Spread about 1 cup of chicken mixture over the noodles followed by 1 cup of cheese. Repeat layers, finishing with the remaining cheese on top.

Bake, uncovered, until the lasagna is hot and bubbly, about 45 minutes. Let it cool for 10 to 15 minutes before serving.

The lasagna can be assembled and kept in the fridge for up to 24 hours in advance; just add 15 minutes to the cooking time when baking. It can also be frozen for up to three months; wrap the lasagna pan in foil and freeze until solid. To cook, bake the frozen lasagna, covered, for 1 hour and 15 minutes, then uncover and bake another 30 to 45 minutes until fully cooked.