Heat a large saucepan over medium-high heat. Add in ground beef and onion and cook until beef is cooked through and onions are soft, about 7 to 10 minutes. Drain any excess liquids.
Add in garlic and tomato paste and toast 2 minutes. Add in crushed tomatoes, tomato sauce, sugar, oregano, salt, pepper, and basil. Bring to a simmer, reduce heat to medium-low, and continue simmering 10 to 15 minutes.
Preheat oven to 350 degrees Fahrenheit. Lightly grease a 9×13 pan.
Spoon 1/4 cup of the meat sauce into the bottom of your 9×13 pan and spread it out to lightly cover. Add in 1/3 of the ravioli. Spoon on 1/3 of remaining meat sauce, top with 1 cup mozzarella cheese, and 1/3 cup Parmesan cheese. Continue with this pattern to create 3 complete layers.
Cover the pan loosely with aluminum foil. Bake in the 350 degree oven for 40 to 45 minutes, until cheese is bubbling and starting to brown. Remove foil during the last 10 minutes of baking.