Instructions

1. Arrange a rack in the middle of the oven and heat the oven to 350°F. Line a rimmed baking sheet with parchment paper or aluminum foil.
2. Grate 1 medium yellow onion on the large holes of a box grater (about 1 cup). Mince 2 garlic cloves. Pick the leaves from 10 fresh parsley sprigs and finely chop (about 1/4 cup).
3. Heat 1 tablespoon vegetable or olive oil in a medium skillet over medium heat until shimmering. Add the onion and cook until the excess moisture evaporates and the onion is translucent, 6 to 8 minutes. Add the garlic and cook until fragrant, about 30 seconds. Transfer to a large bowl and let cool slightly, about 5 minutes.
4. Place 1/2 cup ketchup, 2 tablespoons packed brown sugar, and 2 teaspoons Dijon mustard in a small bowl, and whisk to combine. Transfer half of the mixture (about 1/4 cup) to the bowl with the vegetables. Stir 2 teaspoons apple cider vinegar into the remaining ketchup mixture and set aside for glazing the meatloaf.
5. Add the parsley, 2 large eggs, 2 tablespoons Worcestershire sauce, 2 teaspoons dried Italian seasoning, 2 teaspoons kosher salt, and 3/4 teaspoon black pepper to the bowl of vegetables and stir to combine. Add 1/2 cup dried breadcrumbs or panko, and stir until no dry spots remain. Add 2 pounds ground turkey and mix with your hands until just combined, but do not overwork the mixture.
6. Transfer the meatloaf mixture to the baking sheet and shape into a 9x5-inch loaf. Spread the reserved glaze evenly over the meatloaf.
7. Bake until an instant-read thermometer inserted into the center of the meatloaf registers at least 160°F, about 45 minutes. Let cool for at least 10 minutes before slicing and serving. Garnish with more chopped fresh parsley if desired.