4
Bring the cast iron out of the oven and top the pizza with a good handful of the cheeses, squash, goat cheese and walnuts. Stick back in the oven and cook another 10 to 15 minutes, or until the dough is cooked through and the cheese is browned and bubbly on top. Repeat with remaining pizza. (Or, if you have two cast iron skillets, you can cook them at the same time.)