PREPARE OVEN: Preheat the oven to 350°F. Lightly coat a 9x13 baking dish with nonstick spray.
MIX MEATBALL BASE: In a large bowl, add 1 pound lean ground beef, 1 cup Italian bread crumbs, 1/2 cup whole milk, 2 large eggss, 2 tablespoons ketchup, 1 tablespoon balsamic vinegar, 1/2 teaspoon ground nutmegg, 1/2 teaspoon fresh ground black pepper, 1/2 teaspoon kosher salt, 1 teaspoon onion powder, 1/2 teaspoon garlic powder, and 2 tablespoons Italian seasoning. Mix gently with your hands until combined. Do not overwork.
SHAPE MEATBALLS: Scoop 1-tablespoon portions and roll into balls. Place them in the prepared 9x13 baking dish in a single layer. Set aside.
MAKE SAUCE: In a medium bowl, whisk together 1 cup ketchup, 1/4 cup balsamic vinegar, 1/4 cup packed brown sugar, and 1 cup water until smooth.
BAKE: Pour the balsamic sauce evenly over the meatballs. Bake for 30 minutes, or until the meatballs reach 165°F.
GLAZE: Spoon some of the hot sauce from the pan over the meatballs to glaze them before serving.
SERVE: Serve warm with toothpicks for easy grabbing.
Notes
Make-Ahead: Shape the meatballs up to 24 hours in advance. Store covered in the refrigerator. Bake just before serving.Storage: Store cooked meatballs in an airtight container for up to 4 days. Keep the glaze and meatballs together so they stay moist.Reheating: Warm gently in a saucepan over medium-low heat or in a 300°F oven for 10 to 12 minutes. Add a splash of water if the glaze thickens too much.Freezing: Freeze cooked meatballs and glaze for up to 3 months. Thaw overnight in the refrigerator, then reheat until warmed through.Shortcut Tip: Double the glaze if you like extra sauce for dipping or drizzling.Serving Tip: These taste best when served warm with toothpicks for easy grabbing.• For larger meatballs (1 ½ tablespoons each), bake 35 to 40 minutes or until 165°F internally. Yield will be about 20 to 24 meatballs.