Preheat your oven to 350°F (175°C).
In a large bowl, combine ground beef, breadcrumbs, onion, egg, and milk.
Season the mixture with salt and pepper.
Mix the ingredients until well combined.
Roll the mixture into meatballs, about 1 inch in diameter.
Place meatballs on a baking sheet lined with parchment paper.
In a separate bowl, mix grape jelly and barbecue sauce until smooth.
Pour the sauce over the meatballs, ensuring they are well-coated.
Bake in the preheated oven for 25-30 minutes, or until cooked through.
Serve warm, garnished with fresh parsley if desired.