Place cubed potatoes in a large pot of cold, salted water. Bring to a boil and cook until fork-tender, about 15–20 minutes. Drain well.
Return potatoes to the pot. Add milk, butter, and sour cream. Mash until smooth and fluffy. Season with salt and pepper to taste. Set aside and keep warm or refrigerate if making ahead.
2. Make the Meatloaf Mix
Preheat your oven to 375°F (190°C). Lightly grease a 12-cup muffin tin with nonstick spray.
In a large mixing bowl, combine the ground beef, chopped onion, garlic, breadcrumbs, eggs, milk, Worcestershire sauce, BBQ sauce, smoked paprika, salt, and pepper. Mix until just combined—do not overwork.
3. Assemble and Bake
Divide the meatloaf mixture evenly among the muffin cups, pressing down lightly. Bake for 20–25 minutes, or until the internal temperature reaches 160°F (71°C).
During the last 5 minutes of baking, brush each meatloaf cupcake with additional BBQ sauce and return to the oven to caramelize.
