Preheat your oven to 350°F (175°C).
In a large bowl, combine the ground beef, bread crumbs, milk, eggs, ketchup, onion, garlic, Worcestershire sauce, salt, pepper, and thyme. Mix until just combined, avoiding overmixing to keep the meatloaf tender.
Transfer the mixture into a loaf pan or shape it into a loaf on a baking sheet lined with foil.
In a small bowl, mix together the ingredients for the glaze: ketchup, brown sugar, and apple cider vinegar.
Spread the glaze evenly over the top of the meatloaf.
Bake in the preheated oven for about 1 hour or until the meatloaf reaches an internal temperature of 160°F (71°C).
Let the meatloaf rest for 10 minutes before slicing. This helps retain the juices.