Preheat oven to 500ºF.
Heat a large sauté pan over high heat, add the olive oil then the mushrooms, and cook until just done, seasoning with salt and pepper.
Cut the dough ball in half, and stretch each to fit a 10 inch, greased pizza pan.
Spread about half of the pesto over each crust.
Top each pizza with half of the cooked mushrooms.
Top each pizza with half of the fresh mozzarella.
Cook the pizzas until the cheese is slightly browned, about 8-10 minutes.
Remove the pizzas from the oven, and place slices of prosciutto on top immediately.
Let the pizzas rest for about 3 minutes, slice, and serve.