Springtime peas and mint leaves offer a crisp finish to this one-of-a-kind pie from Jim Lahey, author of "My Pizza."
Place a pizza stone in a gas oven on a rack about 8 inches from the broiler. Preheat oven on bake at 500 degrees for 30 minutes. Switch to broil for 10 minutes. If broiler is on the bottom of the oven, place stone in broiler and preheat on low for 20 minutes; increase heat to high and heat 5 minutes more. If using an electric oven, place stone on a rack about 4 inches from the top heating element; preheat on bake at 500 degrees for 30 minutes. Open oven door a few inches and leave ajar about 30 seconds. Close and switch to broil for 10 minutes.
Generously flour dough, hands, and work surface. Press dough down and gently stretch it out to 6 to 8 inches. Very carefully continue the process, massaging it into a round disk of 10 to 12 inches, shaping with the palms of your hands and your fingers; you want some of the bubbles to remain in the dough. It should look slightly blistered. Flour a pizza peel and lift dough onto the center.
Spoon bechamel over surface of dough and spread evenly, leaving a 1-inch border. Sprinkle surface with Parmigiano. Evenly distribute mozzarella and prosciutto over the top. Sprinkle with peas.
Using quick, jerking motions, slide pizza onto stone. Broil until top is bubbling and crust is nicely charred but not burned, 3 to 3 1/2 minutes for gas and about 5 minutes for electric. Transfer pizza to serving platter and top with mint; slice and serve immediately.