Preheat the Oven: Preheat oven to 375°F. Lightly grease or line a 10x15-inch sheet pan with foil for easy cleanup.
Mix the Meatloaf Base: Place 2 pounds lean ground beef and 1 1/2 cups Italian style breadcrumbs in a large mixing bowl. Pour 3/4 cup whole milk over the breadcrumbs to moisten. Add 2 large eggs, 3 tablespoons ketchup, 2 tablespoons balsamic vinegar, 1 teaspoon kosher salt, 1 teaspoon onion powder, 1/2 teaspoon fresh ground black pepper, and 1/2 teaspoon ground nutmeg (if using). Gently combine with clean hands or a wooden spoon, being careful not to overmix, which can make the meatloaf dense.
Shape the Meatloaf: Press the mixture evenly into the prepared sheet pan, spreading to the edges in a flat layer about 3/4-inch thick.
Prepare the Glaze: In a small bowl, stir together 3/4 cup ketchup or BBQ sauce, 3 tablespoons packed light brown sugar, and 2 tablespoons balsamic vinegar until smooth. Spread evenly over the meatloaf.
Bake: Bake for 20–23 minutes, or until the internal temperature reaches 160°F. For a caramelized finish, broil for an additional 3–4 minutes, watching closely to prevent burning.
Rest and Slice: Remove from the oven and let the meatloaf rest for 5 minutes before slicing. This allows juices to redistribute for a moist, easy-to-slice result.
Notes
Make-Ahead Tips: Prepare the meat mixture and glaze separately up to 24 hours in advance. Cover tightly and refrigerate. When ready to bake, press mixture into pan, spread with glaze, and bake as directed (adding a few extra minutes if chilled).Storage: Store leftovers in an airtight container in the refrigerator for up to 4 days.Reheating Tips: Warm slices in a 300°F oven for 10–12 minutes or in the microwave at 50% power until heated through. For best results, cover with foil or a damp paper towel to prevent drying.Freezing Tips: Freeze individual slices wrapped tightly in plastic wrap and foil for up to 3 months. Thaw overnight in the refrigerator before reheating.