HEAT grill to medium heat.
MIX sausage, beef, 3/4 cup cheese and egg; shape into 6 (1/2-inch thick) patties.
GRILL 5 to 6 min. on each side or until done (160ºF), toasting cut sides of buns on the grill for the last minute. Meanwhile, combine remaining cheese, basil and dressing.
FILL buns with lettuce, tomatoes, burgers and cheese mixture.