1. Cook pasta according to package directions. Meanwhile, in a large nonstick skillet, melt butter with oil over medium-high heat. Add mushrooms, reduce heat to medium and saute until softened and just starting to brown, 8 to 10 minutes. Add cream and simmer over high heat until reduced slightly, about 1 minute. Stir in chicken, peas and cheese. Remove from heat; salt and pepper to taste. Toss with pasta and 2 tablespoons parsley. Transfer to a large serving bowl and sprinkle with remaining 2 tablespoons parsley. Serve with additional cheese on the side.
1. Heat oven to 450 degrees F and place rack in center. Rinse chicken and pat dry. In a roasting pan, toss together chicken, tomatoes, onion and oil. Arrange chicken, bone side down, over tomatoes and onion; sprinkle with salt and pepper. Roast until chicken is almost cooked through, 30 to 35 minutes.
2. Heat broiler and place rack 6 inches from heat. Broil until chicken is browned and cooked through, 4 to 6 minutes.