Melt butter in a skillet over medium heat. Cook and stir garlic in hot butter until fragrant, 1 to 2 minutes. Stir onion, green pepper, and cilantro into garlic; cook and stir until the onion is softened, 5 to 10 minutes.
Cook and stir ground beef in a large skillet over medium heat until browned, 5 to 10 minutes; drain fat. Increase heat to medium-high. Stir brown sugar, mustard, Worcestershire sauce, Italian seasoning, onion powder, Greek seasoning, hamburger seasoning, garlic powder, black pepper, smokehouse maple seasoning, smoked salt, and nutmeg into ground beef mixture; cook until boiling, 4 to 6 minutes.
Stir onion mixture into beef mixture; reduce heat to simmer.
Pour barbeque sauce, ketchup, and apple cider vinegar into beef mixture; stir, cover, and simmer until sauce is thickened, 30 minutes. Scoop beef into hamburger buns and serve.