In a large slow cooker add the grape jelly, chili sauce, and cayenne pepper. Whisk to combine. The sauce will be a tad lumpy because of the jelly, but do your best to whisk it until smooth.
Add the frozen meatballs to the sauce. Gently stir in the meatballs until fully coated by the sauce.
Cook on low for 5-6 hours. Or high for 2-3 hours.
Serve as an appetizer or over rice for a main dish.
A great variation would be to use BBQ sauce in place of the chili sauce. You can make this recipe with homemade meatballs too. I suggest cooking the meatballs before placing them in the slow cooker. If you didn’t cook the meatballs the excess grease from the meat would be in the sauce.