Line the Crockpot with aluminum foil and spray with nonstick spray.
In a large bowl, mix all the meatloaf ingredients together.
2 pounds ground beef, ½ onion, ½ cup breadcrumbs, ¼ cup milk, ¼ cup ketchup, 1 tablespoon Worcestershire sauce, 1½ teaspoons kosher salt, 1 teaspoon Italian seasoning, ½ teaspoon ground black pepper, ½ teaspoon garlic powder, 2 large eggs
Form the mixture into a loaf shape.
Transfer the loaf to the Crockpot.
Cover and cook on low for 3 hours.
While the meatloaf is cooking, make the glaze by combining the ketchup, brown sugar, vinegar, garlic powder, and onion powder in a small dish.
¾ cup ketchup, 2 tablespoons brown sugar, 2 tablespoons red wine vinegar, ½ teaspoon garlic powder, ½ teaspoon onion powder
Remove the lid and spread the glaze over the meatloaf.
If desired, transfer the meatloaf to a baking sheet and broil for 4-5 minutes.