Preheat oven to 350°. Cook spaghetti according to package directions. , Meanwhile, in a large bowl, beat egg, milk and salt. Drain spaghetti; add to egg mixture and toss to coat. Transfer to a greased 13x9-in. baking dish., In a large skillet, cook beef, sausage, onion and green pepper over medium heat until meat is no longer pink; drain. Stir in spaghetti sauce and tomato sauce. Spoon over the spaghetti mixture. , Bake, uncovered, 20 minutes. Sprinkle with the cheese. Bake 10 minutes longer or until cheese is melted. Let stand 10 minutes before cutting. Freeze option: Cool spaghetti completely before tossing with egg mixture. Transfer to baking dish; cover and refrigerate. Meanwhile, prepare meat sauce and cool completely before spooning over spaghetti mixture. Cover and freeze unbaked casserole. To use, partially thaw in refrigerator overnight. Remove from refrigerator 30 minutes before baking. Preheat oven to 350°. Bake as directed, increasing time as necessary to heat through and for a thermometer inserted in center to read 165°.