1 can (8 ounces) mushroom stems and pieces, drained
1 tablespoon butter
14 manicotti shells, cooked and drained
6 tablespoons butter
6 tablespoons all-purpose flour
1/4 teaspoon salt
3-1/2 cups 2% milk
3 cups shredded Monterey Jack or cheddar cheese
4 tablespoons shredded Parmesan cheese, divided
In a large bowl, beat cream cheese until fluffy. Beat in the sour cream, parsley, salt and pepper until blended. Stir in chicken. In a small skillet, cook onion and mushrooms in butter until tender; add to chicken mixture. Stuff into manicotti shells.
In a large saucepan, melt butter. Stir in flour and salt until smooth. Gradually whisk in milk. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir in 2-1/2 cups Monterey Jack cheese and 2 tablespoons Parmesan cheese just until melted.
Spread about 1/2 cup cheese sauce in each of 2 greased 11x7-in. dishes. Top with stuffed shells and remaining sauce.
Cover and bake at 350° for 25 minutes. Uncover; sprinkle with remaining cheeses. Bake 10-15 minutes longer or until bubbly and cheese is melted.