Preheat your oven to 350°F (175°C).
In a large bowl, combine ground beef, breadcrumbs, and milk.
Add diced onion and minced garlic to the mixture.
Crack in the egg and mix well to combine all ingredients.
Season with salt, pepper, Worcestershire sauce, and thyme.
Transfer the mixture to a loaf pan and shape it into a loaf.
Spread ketchup over the top.
Bake for 1 hour.
Check for doneness with a meat thermometer.
Let it rest for 10 minutes before slicing.