Cook ground beef and chopped onion in a large skillet over medium heat, breaking up the ground beef into small crumbles as it cooks.
When beef is cooked through drain off any excess grease.
Add minced garlic and cook until fragrant, about 30 seconds.
Add marinara sauce to the skillet.
Fill glass marinara jar half full with water (about 12 oz) and add it to the skillet, stir to combine.
Stir in Italian seasoning, salt and pepper and bring sauce to a simmer.
Once sauce simmers, add cheese ravioli to the skillet. Use a spatula or wooden spoon to move them around making sure they are covered with sauce.
Place a lid on the skillet and simmer ravioli for 15-20 minutes or until pasta is cooked al dente.
NOTE: Check pasta package directions to get an idea for how long to simmer the ravioli. Refrigerated pasta will take less time to cook than frozen pasta.
Occasionally stir sauce gently to prevent pasta from sticking or burning on the bottom of the pan.
Once pasta is cooked, top with grated Parmesan cheese and a generous layer of grated Mozzarella cheese.
Place lid back on the skillet and lower heat to lowest setting. Cook until cheese is melted, about 4-5 minutes.
If desired, top with chopped basil to serve.