In a medium bowl, combine the meat, Parmesan cheese, onion, parsley, sea salt, black pepper, and garlic. Add the egg and olive oil and mix well with your hands.

Shape the mixture into 18 meatballs, adding a little almond flour if it is too soft.

In the slow cooker, add the marinara sauce and place the meatballs into the sauce.

Cover and cook on LOW for 3 to 4 hours, or until the meatballs are no longer pink in the middle.

Place the meatballs on a serving dish, and garnish with parsley. Serve with the remaining sauce for dipping.