Spinach Chicken Parmesan Meatballs in Creamy Tomato Sauce



For the sauce:
1 tablespoon olive oil
1/4 cup chopped onion
1 tablespoon tomato paste
1 clove garlic, minced
2 tablespoons fresh parsley, chopped
2 tablespoons fresh basil, chopped
1 teaspoon dried oregano
1/2 teaspoon red pepper flakes
1 (28 ounce) can crushed tomatoes
1/4 cup heavy cream

For the meatballs:
1 1/2 pounds ground chicken
3 ounces organicgirl baby spinach, chopped into small pieces
1/3 cup dried panko bread crumbs
1/4 cup diced onion
1/3 cup + 2 tablespoons freshly grated Parmesan cheese, divided
1/2 teaspoon kosher salt
1/4 teaspoon ground black pepper
3 cloves garlic, minced
1 egg, lightly beaten
2 tablespoons olive oil
4 ounces shredded mozzarella
minced fresh basil, for garnish