Preheat Oven: Preheat your oven to 375°F (190°C). Lightly grease a 12-cup muffin tin or line it with muffin liners.
Mix Ingredients: In a large mixing bowl, combine the ground meat, breadcrumbs, milk, egg, onion, garlic, Parmesan (if using), ketchup, Worcestershire sauce, Italian seasoning, salt, and pepper. Mix until just combined; do not overmix.
Shape and Bake:
Fill Muffin Tin: Divide the meat mixture evenly among the muffin cups, pressing lightly to pack them.
Prepare the Topping:
Mix Topping: In a small bowl, combine the ketchup, brown sugar, and Dijon mustard (if using).
Add Topping: Spoon or brush the topping mixture over each meatloaf muffin.
Bake: Bake in the preheated oven for 20-25 minutes, or until the internal temperature of the meatloaf reaches 165°F (74°C).
Serve:
Cool Slightly: Let the mini meatloafs rest for 5 minutes before removing them from the muffin tin.
Serve Hot: Serve with mashed potatoes, roasted vegetables, or a side salad.