Place poblano chile on a foil-lined baking sheet; broil 10 minutes or until blackened and charred, turning halfway through cooking time.
Lower oven temperature to 425°F.
Place pepper in a zip-top bag and seal; let stand 10 minutes. Carefully remove skin, seeds, and stem, then chop pepper.
Heat large skillet over medium-high heat. Coat pan with oil or cooking spray. Add corn, green onions, garlic, and zucchini; sauté 2 minutes or until just beginning to brown. Stir in milk; cook over medium heat 3–4 minutes or until liquid has almost evaporated. Cool slightly.
In a large bowl, whisk together egg whites, egg, salt, and pepper. Stir in poblano pepper, corn mixture, and cheese.
Unroll pizza dough onto parchment paper. It should form a 13 x 8 inch rectangle; if it doesn't, use your hands to shape it into one. Spread corn mixture over dough, leaving a 1-inch border. Fold edge of dough over corn mixture. Bake for 12–15 minutes or until set. Sprinkle with cilantro and serve with sour cream (if using).