Preheat oven to 350 degrees Fahrenheit. Line a rimmed baking sheet with foil, then parchment paper.
In a skillet, heat the oil and sauté the onion and then garlic until very soft. Transfer to a large bowl.
Now, make the sauce. In a small saucepan, bring the ketchup, vinegar, brown sugar, and cayenne pepper to a boil. Simmer until slightly reduced and syrupy (about 5 minutes).
Next, make the flavored broth. Transfer two tablespoons of the sauce to a blender, and add the broth and parsley. Blend until smooth.
Finally, pull it all together. Start by adding the flavored broth, eggs, breadcrumbs, Parmesan, salt, and pepper to the onion and garlic you set aside earlier. Then, add the ground turkey and mix with your hands to combine.
Transfer meatloaf mixture to the prepared pan and form into a long log (about 12" by 5"), smoothing the surface.
Spread the reserved ketchup sauce mix over the top.
Drape the bacon in a crisscross pattern over the loaf, tucking underneath if needed.
Bake until an instant-read thermometer (inserted in the center) registers 165 degrees Farhrenheit and the bacon is crisp, about 80 minutes (1 hour 20 minutes) later.