Combine mushrooms, oil, salt and pepper in medium bowl; toss to coat. Roast in 400°F oven 30 minutes or until browned and cooked through.
Combine roasted mushrooms and Extra Melt Monterey Jack Cheese Sauce in large saucepan; puree with immersion blender until smooth.
Heat cheese sauce over medium-low heat, stirring frequently. Hold hot until service.
If serving for take-out, place sauce in heat-safe to-go container.
Serve this sauce over steak bites and cauliflower mash.