In the base of a 5 to 6-quart slow cooker crock, combine the whole berry cranberry sauce, sweet chili sauce, fresh orange juice, orange zest, brown sugar, minced garlic, minced rosemary, Dijon mustard, and apple cider vinegar.

Whisk briskly until the cranberry sauce breaks down and forms a uniform, glossy glaze.

Add the halal beef meatballs into the slow cooker. Gently stir with a wooden spoon or spatula until all meatballs are generously coated in the sauce.

Cover with the lid and cook on LOW for 3 to 4 hours (or on HIGH for 2 hours), stirring once halfway through.

Once the meatballs are hot throughout and the glaze is bubbly and rich, turn the slow cooker to WARM. Remove the lid for 5 to 10 minutes to allow the glaze to thicken slightly and cling tightly to the meatballs.

Transfer to a serving platter or keep warm directly in the slow cooker. Garnish with fresh rosemary sprigs, orange slices, and serve with cocktail picks.