Preheat oven to 350°F. In a large bowl, mix together ground beef, garlic, and onion.
Tear the bread into small pieces and add to beef mixture.
Add the milk, Worcestershire sauce, sage, salt, mustard, pepper and egg to the beef mixture. Mix until the ingredients are well integrated.Place the beef mixture in an ungreased baking pan. Shape into an 8×4-inch loaf in the pan, then spread the ketchup over the top.
Bake uncovered 50 to 60 minutes until meat and juices are no longer pink or until a meat thermometer inserted in the center of the loaf reads 160°F and center of loaf is no longer pink. Let loaf sit for 5 minutes. Remove loaf from pan and cut into slices.