Position the rack in the center of the oven and heat the oven to 400°. If you're using a pizza stone, warm it on the rack for 30 minutes.
Melt the butter in a medium skillet over medium heat. Whisk in the flour, then let the mixture cook 1 minute. Slowly whisk in the broth until the mixture is smooth, then cook, whisking constantly, until it thickens and begins to bubble, about 2 minutes. Whisk in the sage, thyme, salt, and pepper and cook 1 minute more. Remove the pan from the heat and let the sauce cool for 10 minutes.
Lightly flour a large baking sheet or a pizza peel, then place the dough on top. Dimple and stretch the dough to fit your baking surface.
Use a large spoon to spread the sauce onto the crust, leaving a 1/2-inch border. Scatter on the cheese, then top it with the vegetables. Sprinkle on the Parmesan.
Bake the pizza until the crust is brown and the cheese has melted and is beginning to bubble, about 20 minutes. Let the pie cool for 5 minutes before serving.