Preheat oven to 375°F (190°C). Grease a standard 12-cup muffin tin.
In a large bowl, mix ground beef, onion, garlic, breadcrumbs, egg, milk, Worcestershire, paprika, salt, and pepper until well combined.
Divide mixture evenly into the muffin tin, pressing gently into each cup.
In a small saucepan over medium heat, combine BBQ sauce, bourbon, brown sugar, and Dijon mustard. Bring to a simmer and cook for 3–4 minutes until slightly thickened.
Brush the tops of each meatloaf cupcake with the bourbon BBQ glaze.
Bake for 20–25 minutes, until meat is cooked through and glaze is sticky and caramelized.
Meanwhile, boil potatoes in salted water until fork tender, about 15 minutes. Drain and mash with butter and milk. Season to taste.
Once meatloaf cupcakes are done, allow to rest for 5 minutes.
Pipe or spoon mashed potatoes onto each cupcake like frosting. Garnish with chives or parsley if desired.