You definitely do not need to precook the mushrooms for your favorite pizza unless you like to eat a type of mushrooms that must be cooked before eating. Most of the mushrooms in the grocery store are safe to eat raw, like baby bellas, buttons, shiitakes, and more. For pizza or homemade flatbread, just slice them thinly, and they'll cook just enough from the heat of the oven. If you have leftover cooked mushrooms or even roasted mushrooms on hand, they taste wonderful on pizza, too! This is a great way to use them up and enjoy a quick dinner at the same time.