Preheat Oven: Preheat your oven to 350°F (175°C).

Cook Spaghetti: Cook the spaghetti according to package instructions, but reduce the cooking time by 1-2 minutes since it will continue to cook in the oven. Once cooked, drain and set aside.

Cook Ground Beef and Onions: In a large skillet, cook the ground beef and chopped onions over medium heat until the meat is no longer pink and the onions are translucent. Drain any excess grease. Add the spaghetti sauce to the skillet and simmer for 5 minutes, stirring occasionally.

Mix Cream Cheese Layer: In a bowl, combine the softened cream cheese, eggs, and melted butter. Beat until smooth.

Layering:

In a greased 9x13 inch baking dish, spread half of the spaghetti.

Layer with half of the cream cheese mixture, spreading it evenly.

Top with half of the meat sauce.

Sprinkle half of the mozzarella and Parmesan cheeses.

Repeat layers.

Bake: Cover with aluminum foil and bake for 40 minutes. Uncover; bake 20-25 minutes longer or until the cheese is melted and bubbly.

Rest and Serve: Let the baked spaghetti stand for 5-10 minutes before serving. This helps it set and makes it easier to cut into portions.

Optional Garnish: Garnish with additional Parmesan cheese or fresh herbs like basil or parsley if desired.

Enjoy your homemade baked spaghetti! It's a comforting, family-friendly dish that's perfect for a cozy dinner.