Set your oven to 350 degrees Fahrenheit. This temperature cooks the meatloaf perfectly. Let it warm up completely before baking.
Combine beef, breadcrumbs, and milk in a bowl. Add eggs, onion, and garlic next.
Season with salt, pepper, and Worcestershire sauce. Mix gently with your hands until combined. Don't overmix or it gets tough.
Transfer mixture to your loaf pan. Press it down gently and evenly.
Shape it into a nice loaf form. Make sure there are no air pockets.
Whisk ketchup, brown sugar, vinegar, and mustard together. This creates a sweet and tangy topping. Pour half over the uncooked meatloaf.
Place the pan in your preheated oven. Bake for 45 minutes uncovered.
Add remaining glaze after 30 minutes. Cook until internal temperature reaches 160 degrees Fahrenheit. Let it rest for 10 minutes before slicing.