Preheat oven to 400 degrees.
Clean mushrooms and scoop out the insides and stem with a spoon.
Place on baking pan, and Drizzle the mushrooms with olive oil. Bake for about for 5 minutes at 400 degrees F
Remove mushrooms from oven, and turn the broiler to High.
Turn the mushrooms into pizzas. Top them with sauce, cheese, and pizza toppings.
Return pan to oven and broil on High for 3 minutes or until cheese has melted and started to brown.
Remove and serve immediately