Preheat oven to 375°F. Spray a 12-cup muffin tin with nonstick spray.
Make the glaze: whisk all glaze ingredients in a small saucepan. Simmer 3–4 minutes until slightly thickened. Set aside.
In a large bowl, combine beef, pork, onion, garlic, eggs, panko, milk, ketchup, Worcestershire, smoked paprika, salt, pepper, onion powder, and cayenne (if using). Stir in cheddar if using. Mix just until combined.
Divide mixture into 12 portions and press into muffin cups.
Wrap each portion with a slice of bacon around the sides. Tuck ends underneath or secure with a toothpick. Brush tops with glaze.
Bake 22–28 minutes, until the center reaches 160°F. Brush with more glaze at the 20-minute mark if desired.
Optional: broil 1–2 minutes after brushing with glaze for a caramelized finish (watch closely). Rest 5–7 minutes.
Make potato frosting: boil potatoes in salted water 12–15 minutes until fork-tender. Drain, return to pot 1 minute to steam off extra moisture. Mash with butter and sour cream, then add warm milk a little at a time until creamy but thick. Season with salt and pepper. Stir in chives and cheddar if using.
Pipe or spoon mashed potatoes onto each meatloaf cupcake. Garnish with chives or an extra drizzle of glaze if you like.