Preheat your oven to 350 degrees Fahrenheit. Grease a 9 by 13 inch baking dish and set aside.
Bring a large pot of water to a roaring boil and cook the spaghetti according to package directions, boiling for 2 minutes less than is indicated on the package, drain the noodles, and rinse in room-temperature water. (Continue to Step 3 while the water is coming to a boil.)
1 pound spaghetti
In a large skillet over medium heat, cook the ground beef, onion, and garlic. Break up the beef and cook until just after the beef is no longer pink and the onions are soft. Drain any excess grease and return the skillet to the heat.
1 pound ground beef, 1 small yellow onion, 2 cloves garlic
Stir in the marinara sauce, Italian seasoning, red pepper flakes, salt, and pepper. Bring to a simmer.
32 ounces marinara sauce, 2 teaspoons Italian seasoning, 1/4 teaspoon red pepper flakes, 1 1/2 teaspoons kosher salt, 1/2 teaspoon black pepper
In a large bowl, toss the cooked spaghetti with the beaten eggs and Parmesan cheese.
2 eggs, 1 cup Parmesan cheese
Pour just enough of the meat sauce into the bottom of the pan to coat it. Then add the spaghetti. Pour the remaining meat sauce over the spaghetti and top with mozzarella.
Cover with aluminum foil and bake for 40 minutes. Uncover and bake for an additonal 20 minutes.
2 cups mozzarella cheese