Preheat the oven to 350°F.

Puree the onion, green bell pepper, and celery in a food processor until smooth.

In a large bowl, whisk together the pureed vegetables, eggs, Heinz 57 Sauce, Worcestershire sauce, thyme, granulated garlic, salt, and pepper. Add the ground beef and breadcrumbs and mix gently, just until combined. Do not overmix.

Shape the meat mixture into a loaf and place it in a baking dish. Bake for 45 minutes.

While the meatloaf is baking, prepare the glaze: combine the ketchup and barbecue sauce in a small bowl and mix well.

Remove the meatloaf from the oven and brush or pour the glaze over the top.

Return the meatloaf to the oven for an additional 15 minutes. Let rest for 5 minutes before slicing and serving.