01 -
Preheat the oven to 350 degrees F (175 degrees C). Grease a 10-inch pie plate with 1 tablespoon butter.
02 -
Bring a large pot of lightly salted water to a boil. Cook spaghetti in boiling water, stirring occasionally, until tender yet firm to the bite, about 12 minutes. Drain and return to the pot.
03 -
Stir Parmesan cheese, beaten eggs, and 2 tablespoons butter into hot spaghetti until well combined. Form the mixture into a crust in the prepared pie plate and set aside.
04 -
Heat a large skillet over medium-high heat. Cook and stir beef, onion, bell pepper, and garlic in the skillet until beef is crumbly and browned, about 5 to 7 minutes. Drain off fat and stir in diced tomatoes, tomato paste, sugar, and oregano. Cook, stirring occasionally, until heated through.
05 -
Spread cottage cheese over the spaghetti crust, then pour in the beef-tomato mixture.
06 -
Bake in the preheated oven for 20 minutes. Sprinkle mozzarella cheese over the top of the pie and continue baking until the cheese is melted, about 5 minutes more.