Heat oven to 350ºF. Reserve 1/4 cup tomato sauce. In large bowl, combine ground beef, remaining tomato sauce, bread crumbs, onion, egg, Worcestershire sauce, thyme, garlic salt and pepper, mixing lightly but thoroughly.
Divide mixture into thirds and shape to form three loaves, each about 1 1/2 inches thick; place on rack in open roasting pan. Combine reserved tomato sauce, brown sugar and mustard; spread over top of loaves.
Bake in 350ºF oven 40 to 45 minutes or until no longer pink and juices run clear. To serve, cut each meatloaf into 1-inch thick slices. By shaping the ground beef mixture into small, two-serving loaves, baking time can be reduced by 30 minutes. Gentle handling when mixing the ground beef with the other ingredients will ensure a moist, tender meatloaf.
