Cook spaghetti following package directions; drain in a colander and rinse well with cool water.
Combine the drained spaghetti, eggs, and Parmesan cheese; toss lightly to blend. Put the spaghetti mixture in a greased 9-inch square baking dish or deep-dish pie plate. Press over the bottom and up sides of pan. this will form a shell to hold the beef mixture.
In a large skillet over medium heat, brown ground beef with onion and mushrooms; drain. Stir in spaghetti sauce. Spoon beef and sauce mixture over spaghetti shell. Top with bell pepper strips and sprinkle with the mozzarella cheese. Place on the oven rack and put a baking sheet or foil under the pan to catch any drips.
Bake at 350° for 25 to 30 minutes.
Calories per serving: 614
Fat per serving: 21.8g