Gather your ingredients. Preheat your oven to 350 degrees F. Grease a deep 9” pie dish.
Cook the spaghetti according to the package directions. Drain and discard the cooking water, then add the spaghetti to a large bowl. Add the butter, eggs, and parmesan cheese to the bowl and toss everything together. Pour the mixture into the greased pie pan and press it into the bottom and sides of the pan to form a crust. It will be a little loose, but that is
Add the olive oil to a large skillet and heat over medium-high heat. Add the ground beef and diced onion and cook until the beef is browned and there is no more pink, for about 10 minutes. Drain any fat from the skillet then stir in the pasta sauce. Set aside.
In a separate bowl, combine all of the ingredients for the cheese-filling layer Stir well, then spread the mixture over the spaghetti crust.
Pour the cooked saucy beef into the pie dish on top of the ricotta cheese mixture.
Bake the spaghetti pie for 20 minutes. The sauce should be bubbling. Remove the pie from the oven and sprinkle with the shredded mozzarella cheese. Return the pie to the oven for 10 more minutes to melt and brown the cheese.
Cool the spaghetti pie for about 10 minutes, then slice and serve!