To make in microwave, combine undrained tomatoes and cheese in 1-1/2-quart microwave-safe dish; cover. Microwave on HIGH 5 minutes or just until cheese melts, stirring after 3 minutes. Remove from microwave; stir until mixture is blended. CAUTION: Dish will be hot; use hot pads. For a double recipe, microwave on HIGH 8 minutes or until cheese melts, stirring after 5 minutes. Drain 1 can of tomatoes if a thicker dip is preferred.