Position the oven rack in the center and preheat to 350°F. Line a rimmed baking sheet with heavy-duty foil, ensuring it is greased with olive oil or non-stick spray.

In a medium-sized bowl, whisk together the ketchup, brown sugar, Dijon mustard, and apple cider vinegar until smooth and well combined. Set aside.

In a small sauté pan, heat the olive oil over medium heat. Sauté the minced onions, stirring occasionally, until softened, approximately 5 minutes. Add the garlic and continue to cook for an additional 1 to 2 minutes, being careful not to brown it. Remove from heat and let the mixture cool slightly.

In a large mixing bowl, whisk together the salt, pepper, paprika, thyme, Worcestershire sauce, Dijon mustard, eggs, and ¼ cup of the prepared glaze. Stir in the cooled onion and garlic mixture. Add the ground turkey and breadcrumbs, mixing everything thoroughly by hand until well incorporated.

Divide the meat mixture in half and form two equally-sized loaves on the prepared baking sheet. Shape them into loaves approximately 1½ inches tall, 6 inches long, and 4 inches wide. Generously coat the loaves with the remaining glaze, allowing it to drizzle down the sides.

Bake for about 45 minutes, or until the meatloaves are thoroughly cooked through. Carefully scrape away any excess fat from the sides of the loaves, then transfer them to a serving platter. Slice, garnish with fresh parsley if desired, and serve warm.