Heat the oven to 400°F. Lightly grease a 12-cup muffin pan. Line a rimmed baking sheet with parchment paper for the vegetables.

Make the stuffing filling. In a small bowl, combine the dry stuffing mix, diced apple, 1/4 cup of the onion, and chicken broth. Let it stand for 5 minutes so the stuffing can absorb the broth.

In a large bowl, gently mix the ground beef, egg, 1 tablespoon of the ketchup, dried sage, salt, black pepper, and the remaining 1/4 cup onion. Stop mixing as soon as the ingredients are combined.

Divide the beef mixture into 8 portions. Press each portion into a muffin cup and make a shallow well in the center. Spoon the apple stuffing into the wells. Wrap one slice of bacon around the edge of each muffin, tucking the ends into the beef. Brush the bacon and exposed beef lightly with the remaining tablespoon of ketchup.

Put the carrots and potatoes on the prepared baking sheet. Toss them with olive oil and spread them in a single layer. Set the muffin pan on the oven rack beside the vegetables.

Bake for 25 to 30 minutes, until the bacon is browned and the meatloaf muffins reach 160°F in the center. Stir the vegetables once during baking. If the bacon needs more color, broil the muffins briefly at the end, watching closely.

Let the muffins rest for 5 minutes before removing them from the pan. Serve with the roasted carrots and potatoes.