Spaghetti and meatballs with a surprise

Ingredients
1/4 cup grated onion
1 teaspoon dried Italian seasoning
1/2 teaspoon salt
1 1/2 pounds ground round
1 garlic clove, minced object
3 ounces part-skim mozzarella cheese, cut into 16 cubes
1 (26-ounce) bottle fat-free pasta sauce
5 1/2 cups hot cooked spaghetti (about 12 ounces uncooked pasta)

Combine first 5 ingredients in a bowl; shape into 16 (1-inch) meatballs. Working with 1 meatball at a time, flatten meatball, and place 1 cheese cube in center of meatball. Gather meatball around cheese cube, sealing well.
Heat a large nonstick skillet over medium-high heat. Add meatballs; cook 6 minutes, browning on all sides. Drain well. Wipe pan with a paper towel.
Return meatballs to pan. Add pasta sauce; bring to a simmer over medium heat. Cover and cook 10 minutes. Serve over pasta.