Preheat your oven to 350°F (175°C). If you're using a baking sheet, line it with parchment paper for easier cleanup.
In a large mixing bowl, combine ground beef, gluten-free bread crumbs, milk, chopped onion, minced garlic, eggs, ketchup, Worcestershire sauce, salt, black pepper, thyme, and Italian seasoning.
Mix all ingredients together using your hands or a spoon until well incorporated. Be careful not to overmix, as it can make the meatloaf tough.
Transfer the meat mixture into the prepared loaf pan, shaping it into a loaf shape.
Spread a thin layer of ketchup on top of the loaf for added flavor and moisture.
Place the loaf pan (or loaf shape on baking sheet) in the preheated oven and bake for 1 hour, or until the internal temperature reaches 160°F (70°C) using a meat thermometer.
Once done, remove the meatloaf from the oven and let it rest for about 10 minutes before slicing.