5 tablespoons butter
2 tablespoons olive oil
4 boneless skinless chicken breasts
2 1/4 teaspoons salt
1 1/4 teaspoons freshly ground black pepper
1 pound white mushrooms, sliced
1 large onion, finely chopped
5 cloves garlic, minced
1 tablespoon chopped fresh thyme leaves
1/2 cup dry white wine
1/3 cup all-purpose flour
4 cups whole milk, room temperature
1 cup heavy whipping cream, room temperature
1 cup chicken broth
1/8 teaspoon ground nutmeg
12 ounces linguine
3/4 cup frozen peas
1/4 cup chopped fresh Italian parsley leaves
2 cups grated cheese (mozzarella, provel, provolone or some combination therein)
1 cup grated Parmesan
1/4 cup dried Italian-style breadcrumbs
Preheat the oven to 450 degrees F.
Generously spray a 13 x 9 inch baking dish with nonstick cooking spray.
Melt 1 tablespoon each of butter and oil in a deep large nonstick frying pan over medium-high heat. Sprinkle the chicken with 1/2 teaspoon each of salt and pepper. Add the chicken to the hot pan and cook until pale golden and just cooked through, about 4 minutes per side. Transfer the chicken to a plate to cool slightly. Coarsely shred the chicken into bite-size pieces and place in a large bowl.
Meanwhile, add 1 tablespoon each of butter and oil to the same pan. Add the mushrooms and saute over medium-high heat until the liquid from the mushrooms evaporates and the mushrooms become pale golden, about 12 minutes. Add the onion, garlic, and thyme, and saute until the onion is translucent, about 8 minutes. Add the wine and simmer until it evaporates, about 2 minutes. Transfer the mushroom mixture to the bowl with the chicken.
Melt 3 more tablespoons butter in the same pan over medium-low heat. Add the flour and whisk for 2 minutes. Whisk in the milk, cream, broth, nutmeg, remaining 1 3/4 teaspoons salt, and remaining 3/4 teaspoon pepper. Increase the heat to high. Cover and bring to a boil. Simmer, uncovered, until the sauce thickens slightly, whisking often, about 10 minutes. Remove from heat and add 2 cups of cheese.
Meanwhile, bring a large pot of salted water to a boil. Add the linguine and cook until it is tender but still firm to the bite, stirring occasionally, about 9 minutes. Drain. Add the linguine peas, and parsley to the chicken mixture. Pour mixture into prepared baking dish. Pour sauce over mixture. Stir a bit so sauce coats the the mixture and is blended.
Stir the cheese and breadcrumbs in a small bowl to blend. Sprinkle the cheese mixture over the pasta. Bake, uncovered, until golden brown on top and the sauce bubbles, about 25 minutes.