1 package (12 ounces) jumbo pasta shells
1-1/2 pounds boneless skinless chicken breasts, cut into 1/2-inch cubes
2 tablespoons olive oil, divided
1/2 pound sliced baby portobello mushrooms
1 egg, lightly beaten
1 carton (15 ounces) ricotta cheese
3-1/4 cups grated Parmesan cheese, divided
1 cup (4 ounces) shredded part-skim mozzarella cheese
1 teaspoon dried parsley flakes
3/4 teaspoon salt
1/2 teaspoon pepper
1/2 cup butter, cubed
2 garlic cloves, minced
2 cups heavy whipping cream
Cook pasta according to package directions.
Meanwhile, in a large skillet, brown chicken in 1 tablespoon oil. Remove and set aside. In the same pan, saute mushrooms in remaining oil until tender; set aside. In a small bowl, combine the egg, ricotta, 1-1/2 cups Parmesan, mozzarella and seasonings.
Drain and rinse pasta with cold water; stuff each shell with about 1 tablespoon of cheese mixture. Place in a greased 13-in. x 9-in. baking dish. Top with chicken and mushrooms.
In a large saucepan over medium heat, melt butter. Add garlic; cook and stir for 1 minute. Add cream; cook 5 minutes longer. Add 1-1/2 cups Parmesan cheese; cook and stir until thickened.
Pour sauce over the casserole. Sprinkle with remaining Parmesan cheese. Cover and bake at 350° for 30 minutes. Uncover; bake 10-15 minutes longer or until bubbly.