Wash the mushrooms and remove the stems. It is important to thoroughly dry the mushrooms after you wash them. Mushrooms release liquid when they cook and that will leave you with a soggy pizza crust. Be sure to pat the mushrooms dry on both sides with paper towels before you add toppings.
Place the mushrooms bottom side up on the cookie sheet and evenly spread the sauce onto each.
Sprinkle the mozzarella over each mushroom. Then add your toppings.
Bake for 10-15 minutes or until the cheese is starting to brown.
Remove from the oven and let the pizzas cool for 5 minutes before serving.