Preheat the oven to 350°F (175°C).

Cook the spaghetti according to package directions in a large pot of salted water (add about a tablespoon of sea salt or kosher salt to the boiling water).

While the spaghetti is cooking, brown the ground beef and chopped onion in a large skillet over medium heat. Cook until the beef is fully browned and crumbled.

Turn off the heat and drain any excess grease from the beef mixture.

Return the beef to the skillet and stir in the spaghetti sauce. Keep warm until ready to assemble.

Once the spaghetti is cooked and drained, return it to the pot. Add the butter and stir until melted and evenly coating the spaghetti.

Stir in the beaten eggs and grated parmesan cheese quickly, mixing until fully combined.

Divide the spaghetti mixture evenly between two 9-inch pie pans.

In a medium bowl, combine the ricotta cheese, minced garlic, and Italian seasoning. Mix until smooth.

Spoon the ricotta mixture evenly over each pan of spaghetti, spreading it out with the back of a spoon or a butter knife.

Top each pie with the prepared meat sauce, dividing it evenly between both pans.

Sprinkle the shredded mozzarella evenly over both pies, using about 1 cup per pie. Add dried parsley on top if desired.

Bake the pies in the preheated oven for about 25 to 30 minutes, or until heated through and the cheese is fully melted and slightly golden.

Let cool for a few minutes before slicing and serving.