01 - Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
02 - In a large bowl, combine ground beef, breadcrumbs, Parmesan, egg, milk, minced garlic, onion powder, salt, pepper, and chopped parsley. Mix gently until just combined. Form the mixture into 12 equal-sized meatballs.
03 - Arrange the meatballs on the prepared baking sheet. Bake for 18–20 minutes, or until they are browned and cooked through.
04 - While meatballs are baking, whisk together cola, ketchup, brown sugar, apple cider vinegar, Worcestershire sauce, smoked paprika, chili powder, and cayenne pepper (if using) in a saucepan over medium heat. Bring to a simmer and cook for 10–12 minutes, stirring occasionally, until the sauce has thickened.
05 - Once baked, toss the meatballs in the prepared cola BBQ sauce until they are thoroughly coated.
06 - In a separate bowl, combine shredded cabbage, shredded carrots, mayonnaise, Dijon mustard, apple cider vinegar, salt, and pepper. Mix well and chill until ready to serve.
07 - Brush the slider buns with melted butter. Toast them in a skillet or in the oven until they are golden brown.
08 - On the bottom half of each toasted bun, place a spoonful of the prepared slaw. Top the slaw with a glazed meatball. Add sliced pickles, if desired. Place the top bun on each slider and serve immediately.