First Step: Prep Ingredients and Equipment
Gather all ingredients: frozen cooked meatballs, chili or barbecue sauce, and grape jelly. Preheat your slow cooker on high or prepare a stovetop pot for simmering sauce. No need to thaw meatballs beforehand if using a slow cooker.

Second Step: Combine Sauce Ingredients
In a large bowl or directly in the slow cooker insert, mix together the chili sauce or barbecue sauce with the jar of grape jelly. Stir until the jelly is mostly incorporated into the sauce, forming a sweet and tangy base.

Third Step: Add Meatballs
Add frozen bite-sized meatballs to the sauce mixture, gently stirring to coat each meatball evenly. Ensure all meatballs are submerged for uniform cooking and flavor absorption.

Fourth Step: Slow Cook or Simmer
Cover and cook on high for 2 to 2 1/2 hours or on low for 3 to 4 hours in the slow cooker, allowing meatballs to heat through and sauce to thicken slightly. For stovetop, heat sauce over medium-low, add meatballs, and simmer uncovered for 25 minutes, stirring occasionally until heated and thickened.

Fifth Step: Thicken Sauce if Desired
If a thicker sauce is preferred, uncover slow cooker during the last 30 minutes stirring occasionally. Alternatively, stir in a cornstarch slurry (equal parts cornstarch and water) and simmer briefly until sauce thickens on the stovetop.

Final Step: Serve and Garnish
Serve grape jelly meatballs warm, garnished with fresh parsley if desired. Offer toothpicks for easy party serving or present over rice, mashed potatoes, or in slider rolls for a hearty meal. Leftovers store well and reheat easily.