Puree the chopped onion, green bell pepper, and celery in a food processor until smooth.
In a large bowl, whisk together eggs, Heinz 57 sauce, Worcestershire sauce, thyme, salt, pepper, granulated garlic, and the pureed vegetables. Mix well.
Add ground beef and bread crumbs to the mixture. Stir gently to combine, being careful not to overmix.
Shape the meat mixture into a loaf and place in a baking dish.
Bake for 45 minutes.
While meatloaf is baking, prepare the glaze by mixing together ketchup and barbecue sauce.
Remove meatloaf from oven and brush or pour the glaze over the top.
Return meatloaf to the oven for an additional 15 minutes.
Let rest for 5 minutes before slicing and serving.