Preheat the oven to 375°. In a medium skillet, heat the olive oil. Add the onion and garlic and cook over moderate heat until softened, about 8 minutes. Let stand until cooled to room temperature, about 15 minutes.
In a large bowl, mix the bread crumbs with the milk until evenly moistened. Add the 2 teaspoons of ketchup and the onion mixture, egg, Worcestershire sauce, thyme, salt, black pepper and mustard and mix until blended.
In a food processor, pulse the bacon until finely chopped; add it to the bread crumb mixture. Add the ground beef, veal and pork and mix gently with your hands until evenly combined.
In a medium roasting pan, form the meat into a 9-by-5-inch loaf. In a small bowl, mix the remaining 1/4 cup of ketchup with the brown sugar and cayenne. Spread the ketchup over the top of the meat loaf. Bake for about 1 hour and 10 minutes, until the glaze is browned and an instant read thermometer inserted in the center of the meat loaf registers 160°. Let the meatloaf rest for 10 minutes. Cut into slices and serve.