Created by KittenCal on November 19, 2012
Step 1: Genorously grease then preheat a gas or charcoal grill.
Step 2: Using a pastry brush, liberally brush olive oil over both sides of the mushrooms, then season them with salt and pepper. Grill until the mushrooms are heated through and tender, about 5 minutes per side.
Step 3: Preheat the oven to 400 degrees F. Grease a 13 x 9-inch baking dish.
Step 4: Spread about 1 cup or a little more of the marinara sauce on the bottom of baking dish. Place the grilled mushrooms on top of the marinara sauce and top with the remaining marinara sauce. Sprinkle with the cheeses and top with the butter pieces.
Step 5: Bake until the cheese melts and the top is golden, about 15 minutes. Serve.