Preheat oven to 375 degrees F. Cook pasta according to package directions; rinse and drain. Set aside. Melt 1 tablespoon butter in large saucepan on medium heat. Cook and stir sausage and onions 3 to 5 minutes or until onions are tender. Stir in Alfredo sauce, and half and half. Bring to boiling, stirring constantly; reduce heat. Simmer 1 minute. Remove saucepan from heat. Stir in cheese and black pepper until cheese is melted. Stir in pasta and sausage mixture. Pour mixture into lightly sprayed 139-inch baking dish. Sprinkle evenly with combined bread crumbs and 1/4 cup melted butter. Bake 20 to 25 minutes or until crumbs are golden brown and pasta mixture is hot and bubbly.