Preheat oven to 350°F (175°C). Lightly grease a 9x5-inch loaf pan or line a baking sheet with parchment paper.
In a small bowl, combine breadcrumbs and milk. Let sit for 5 minutes to soften.
In a large mixing bowl, combine ground beef, soaked breadcrumbs, egg, onion, 1/4 cup ketchup, Worcestershire sauce, salt, pepper, garlic powder, and thyme. Mix gently with hands until just combined; do not overmix.
Transfer meat mixture to the prepared loaf pan or shape into a loaf on the baking sheet. Smooth the top.
In a small bowl, mix 1/4 cup ketchup, brown sugar, and apple cider vinegar to make the glaze. Spread half over the top of the meatloaf.
Bake for 45 minutes. Remove from oven and spread remaining glaze over the top. Return to oven and bake for an additional 15 minutes, or until internal temperature reaches 160°F (71°C).
Let meatloaf rest for 10 minutes before slicing and serving.
Notes
For best results, use a meat thermometer to ensure the internal temperature reaches 160°F. Leftovers can be stored in an airtight container in the refrigerator for up to 3 days.