Meatballs and Marinara

1. Heat oil in Dutch oven until shimmering. Add onions, tomato paste, 6 garlic cloves, oregano, pepper flakes, and 1/4 teaspoon salt. Cook until golden, about 8 minutes. 2. Transfer half of onion mixture to large bowl; set aside. Add wine to the pot with the remaining onion mixture. Cook until slightly thickened, about 2 minutes. Stir in tomatoes, then transfer to the slow cooker. 3. Add 1/2 cup parmesan, the mozzarella, sausage, eggs, 3/4 teaspoon salt, and remianing garlic to the bowl with reserved onions. Mash until smooth. Add the beef and cream and knead until well combined. Form into twelve 2-inch meatballs. 4. Microwave the meatballs on a large plate until the fat renders and the meatballs are firm, 4 to 7 minutes. Nestle the meatballs into the slow cooker, discarding the rendered fat. Cover and cook on low until meatballs are tender and the sauce is slightly thickened, 4 to 5 hours. 5. Skim the fat. Stir in the basil and remaining 1/2 cup parmesan. Season with salt.