The original recipe called for Italian sausage, which would also be fantastic. I happened to stock up on frozen pre-made meatballs just before access to the grocery store became more limited, so that’s what I used!
Place meatballs in a medium saucepan with 1 1/2 cups of the marinara sauce.
Bring to a boil then reduce to a simmer and continue simmering, stirring occasionally, while preparing the rest of the dish.
You want to heat the meatballs thoroughly.
Preheat oven to 400 F.
Spray a large muffin pan with non-stick spray.
Use a pan that holds 12 muffins. You can get by with a 9-muffin pan and enjoy the remaining meatballs on the side (or just heat 9!).
Cook the halved spaghetti according to the package directions.
Rinse and drain well.
In a bowl, stir together the egg, Parmesan cheese, mozzarella cheese, remaining 1/4 cup of the marinara sauce and spaghetti. Make sure the spaghetti is well coated.
Divide the spaghetti mixture into 12 of the muffin pan cups. Using your finger, make an indentation in the middle of each cup to create a nest.
Bake for 13-15 minutes or until the spaghetti is set. You don't want it to get crunchy, so check it after 13 or so minutes.
Transfer spaghetti nests to a platter. I used a spatula and tongs to both support the nests on the bottoms and sides. Be careful, some may want to fall apart on you. It won't be the end of the earth if they do!
Add a meatball to each nest then divide the sauce over the tops.
Sprinkle with additional Parmesan cheese and a little dried basil and Italian seasoning and serve.