Cook the spaghetti according to the package directions, until it’s al dente, then drain
While the spaghetti is cooking, heat the oven to 400°F
Melt 2 tablespoons butter
Stir the melted butter and the bread crumbs in a small bowl
Heat the remaining 2 tablespoons butter in a 4-quart saucepan over medium heat
Add the onion and cook for 1 minute
Add the mushrooms and cook for 5 minutes or until tender
Add the sherry and cook and stir for 1 minute
Stir in the soup, milk and Parmesan cheese
Add the chicken, peas and cooked spaghetti and toss to coat
Season with salt and pepper
Spoon the chicken mixture into a 13x9x2-inch baking dish
Sprinkle the bread crumb mixture over the chicken mixture
Bake for 25 minutes or until the mixture is hot and the bread crumb mixture is lightly browned
