Prepare the pizza oven or grill for baking pizza at 500°F (see our guide for perfect pizza on the grill).Prepare your grill for indirect cooking at 400°F to roast the squash and onions. Or, if your grill is not available for this task, preheat your indoor oven to 400°F.Spread the onion and squash in a single layer on a cookie sheet covered in parchment. Drizzle with balsamic vinegar and olive oil and sprinkle with salt. Roast at 400°F until caramelized, about 30 minutes, turning once.
With a cooktop burner, toast the hazelnuts in a small pan over medium heat until browned and crunchy. Toss with a little sea salt and reserve.
In a small bowl, combine the ricotta, lemon zest and rosemary leaves with a little olive oil and salt to taste.
Roll out the pizza dough to about 17” and transfer to a pizza prep peel lightly dusted with corn meal. Spread the cheese mixture over the dough. Sprinkle the caramelized squash and onions over the cheese and then add the hazelnuts.
Bake the pizza until the crust is golden brown and the toppings are hot, about 10 minutes.
