Barbecued Cheddar Burgers

3 1/2 pounds lean ground beef
1/2 cup purchased barbecue sauce
1 teaspoon garlic powder
1 teaspoon salt
1 teaspoon ground black pepper

1 cup grated cheddar cheese
12 sesame-seed hamburger buns, lightly toasted
Lettuce leaves
Sliced tomatoes

Mix first 4 ingredients in large bowl until blended. Mix in pepper. Shape half of meat mixture into eight 1/2-inch-thick patties. Shape remaining meat mixture into four 1-inch-thick patties. (Can be made 8 hours ahead. Cover and chill.)

Prepare barbecue (medium-high heat). Grill patties to desired doneness, topping with cheese for last minute of cooking, about 4 minutes per side for medium-rare 1/2-inch-thick patties, and about 6 minutes per side for medium-rare 1-inch-thick patties. Place burgers on bottom halves of buns. Top with lettuce, tomatoes and upper halves of buns.