Preheat your oven to 350°F (175°C).
Warm some olive oil in a skillet set over medium heat, then gently cook the onions and garlic until they become soft and clear.
In a large mixing bowl, combine the sautéed onions and garlic with ground beef, breadcrumbs, milk, eggs, ketchup, Worcestershire sauce, thyme, salt, and pepper.
Stir the mixture gently to combine the ingredients thoroughly but be careful not to over-stir, as this can make the meatloaf tough.
Pour the blend into a loaf pan, shaping it into a uniform loaf.
Brush the top with a layer of ketchup.
Place in an oven preheated to the required temperature and bake for 1 hour, or until the meatloaf is fully cooked.
Allow the meatloaf to sit for 10 minutes after baking to settle the juices before cutting.