Filling- In large non stick skillet, cook mushrooms, sausage and tomatoes over medium heat 8 minutes or until sausage is cooked through, stirring frequently. Remove from heat and drain; cool slightly and stir in shredded cheese and basil.
Prepare burgers. Form meat into 8 1/4 inch thick patties; sprinkle with salt and pepper. Divide filling evenly onto center of 4 patties. Top with remaining 4 patties. Pinch edges to seal.
Place burgers on hot grill. Cover and cook 15 minutes or until internal temp reaches 155 for medium doneness turning once. Top patties with cheese and let melt during last minute of cooking.