Preheat your oven to 375°F (190°C).

In a large mixing bowl, combine the ground beef, finely chopped onion, quick oats, whole milk, eggs, Worcestershire sauce, sea salt, garlic powder, and half of the ketchup. Mix until just combined.

Transfer the meat mixture to a lined baking sheet or greased loaf pan. Form it into a loaf shape, about 2 inches high.

Spread the remaining ketchup evenly over the top of the shaped meatloaf.

Place your meatloaf in the preheated oven and bake for about 45 minutes until the internal temperature reaches 165°F (74°C).

Once baked, let the meatloaf rest for at least 10 minutes before slicing.