Preheat your oven to 350°F (175°C). If desired, line your loaf pan with aluminum foil for easier removal.
In a large mixing bowl, combine the ground beef, gluten-free breadcrumbs, grated onion, milk, eggs, ketchup, Worcestershire sauce, garlic powder, dried oregano, salt, and black pepper.
Using your hands or a spatula, mix all the ingredients together until just combined. Do not overmix, as this can make the meatloaf tough.
Transfer the meat mixture to the prepared loaf pan, shaping it into a loaf.
Spread a thin layer of ketchup on top for added flavor and moisture.
Place the loaf pan on a baking sheet (optional, for easier cleanup) and bake in the preheated oven for about 60 minutes, or until the internal temperature reaches 160°F (70°C).
Once cooked, remove the meatloaf from the oven and allow it to rest for 10 minutes before slicing. This helps keep it moist.
Serve with your favorite sides, such as mashed potatoes or steamed vegetables. Enjoy!