Add the chili sauce, apple butter, maple syrup, molasses, ground cloves, and ground cinnamon to the slow cooker. Stir to combine.
Add frozen meatballs to the prepared sauce. Toss to coat.
Cover and cook on HIGH for 2.5-3 hours or LOW for 4-5 hours. Stirring occasionally so the meatballs won't burn on the edges. Serve as an appetizer or as an entrée over mashed potatoes or rice with roasted veggies.