Heat the oven to 400°F. Lightly grease a 4-cup section of a standard muffin tin.
In a mixing bowl, combine the ground beef, egg, breadcrumbs, onion, milk, Worcestershire sauce, garlic powder, salt, and black pepper. Mix gently until just combined.
Divide the meat mixture into 8 equal portions. Press 4 portions into the muffin cups, making a shallow well in the center of each.
Place one cube of pepper jack in each well. Cover with the remaining meat portions and pinch the edges together to seal the cheese inside.
Wrap two slices of bacon around each muffin, tucking the ends underneath. Brush the tops with barbecue sauce.
Bake until the bacon is browned and the meatloaves reach 160°F in the center, about 25 to 30 minutes. Rest in the tin for 5 minutes before removing and serving.