Heat oil in medium skillet on medium-high heat. Add onions, mushrooms, salt and pepper; cook 8 minutes or until onions are softened, stirring frequently. Reduce heat to medium; add 2 cups FarmToFork™ Marinara Sauce and cook until heated through. Remove pan from heat; cover to keep warm.
Meanwhile, combine meats, salt and remaining 1/2 cup sauce in large bowl. Shape mixture into 6 patties. Grill patties, covered, 4-5 minutes on each side or until cooked through (155°F). Top with cheese during last 2 minutes of cooking. Fill buns with basil leaves, burgers and Topping.