To a large pot, cook ravioli according to package directions; drain and set aside.

Preheat broiler to high.

To a large, high-sided, ovenproof skillet, add the olive oil, onion, and saute over medium-high heat for about 3 minutes, or just until onion begins to soften.

Add the ground beef, crush and crumble with a spatula as it cooks, and stir beef and onions frequently as they cook to ensure even cooking.

After beef has completely cooked, add the garlic, Italian seasoning, salt, pepper, stir to combine, and cook for about 1 minute, or until garlic is fragrant.

Add the crushed tomatoes, add the cooked ravioli, and stir to combine.

Evenly sprinkle with the mozzarella, then the Parmesan, and place skillet under the broiler for about 5 minutes, or until cheese is as browned as desired, making sure to check very frequently for doneness. Because all broilers vary dramatically in their intensity, start checking after 3 minutes and do not leave your food unattended because you don't want it to burn; noting that it could possibly take longer than 5 minutes, just keep an eye on it. Remove the skillet from under the broiler when the cheese is as melted and golden as desired.