Step 1: Pre-heat oven to 200c
Step 2: place to mushrooms head up on a tray, and oven cook for 10minutes.
Step 3: turn the mushrooms over, and spread on the garlic butter.
Step 4: put as much cheese on as you wish, then pop back in the oven till the cheese has melted.
Step 5: really quick and easy to do, cheap, and tastes amazing too!