Preheat the oven to 350°F (175°C). Line a rimmed baking sheet with heavy-duty aluminum foil and lightly grease it with olive oil or non-stick cooking spray.
Make the Glaze: In a medium bowl, whisk together ketchup, brown sugar, apple cider vinegar, and Dijon mustard. Set aside.
Sauté the Aromatics: Heat olive oil in a small pan over medium heat. Add the chopped onions and cook until softened, about 5 minutes. Add minced garlic and cook for 1-2 minutes. Set aside to cool.
Prepare the Meatloaf Mixture: In a large bowl, combine salt, pepper, paprika, thyme, Worcestershire sauce, Dijon mustard, eggs, and ¼ cup of the prepared glaze. Whisk until well combined. Stir in the sautéed onion and garlic. Add the ground turkey and breadcrumbs. Mix gently with your hands until combined.
Shape the Meatloaf: Transfer the meat mixture onto the prepared baking sheet. Form two long loaves, each about 1½ inches high, 6 inches long, and 4 inches wide. Brush the remaining glaze over the loaves.
Bake the Meatloaf: Place the baking sheet in the oven and bake for about 40-45 minutes or until the meatloaf reaches an internal temperature of 165°F (74°C).
Rest and Serve: Let the meatloaf rest for 5-10 minutes before slicing. Garnish with fresh parsley, if desired. Serve and enjoy!