1/4 cup plus 2 tablespoons unsalted raw pistachios, coarsely chopped
Extra-virgin olive oil, for drizzling
Put a pizza stone in the oven and preheat the oven to 500°, allowing at least 30 minutes for the stone to preheat.
Work with one piece of dough at a time: On a floured surface, roll or stretch the dough out to a 12-inch round. Transfer the dough to a floured pizza peel. Spread one-third of the cheese on top, leaving a 1/2-inch border all around. Lightly press the cheese into the dough. Top with one-third of both the onion and the rosemary.
Slide the pizza onto the stone and bake for about 4 minutes, until lightly golden and bubbling. Carefully sprinkle one-third of the pistachios over the pizza and bake for 2 minutes longer, until the crust is browned and the onions are very soft. Slide the pizza onto a work surface. Drizzle with olive oil, cut into wedges and serve. Repeat with the remaining dough and toppings.