Preheat the oven to 350 degrees.

Line a rimmed baking sheet with foil. Place a wire rack on top and cover it with foil. Using a knife, slit a few holes in the foil, so the meatloaf grease can drain down onto the baking sheet. Spray the foil lightly with the cooking spray.

In a large bowl, gently combine the ground beef, pork, eggs, Parmesan, bread crumbs, garlic, minced onions, thyme, salt and pepper, and ½ cup of the ketchup.

Shape the meat into a loaf (about 9 inches long) on the foil-covered wire rack on top of the baking sheet.

Top the loaf with the remaining ¼ cup of ketchup and bake for 45 to 60 minutes, or until the internal temperature reaches 160 degrees. Remove the meatloaf from the oven and let it rest for 10 minutes before slicing.

While the meatloaf is baking, make the fried onions. In a medium bowl, combine the onions and buttermilk. Let them sit for 20 minutes.

While the onions are soaking, in a cast-iron skillet, heat the oil to 350 degrees.

In a shallow dish, combine the flour, cayenne, salt, and pepper.

Using tongs, shake the excess buttermilk off the onion slices and dip them into the flour mixture, tossing to coat. Shake the excess flour off the onions and, working in batches, being sure not to overcrowd the pan, carefully place them in the hot oil. Fry the onions until they are golden brown and crisp, flipping once. Remove the onions from the skillet and let them drain on paper towels. Sprinkle the onions with salt.

Slice the meatloaf and top each slice with a handful of fried onions to serve.