Preheat oven to 450. Line baking sheet or pizza pan with parchment paper or sprinkle with cornmeal
Mix flour blend, yeast, xantham gum, and salt in bowl. Whisk in 1 cup water water, oil, egg whites, honey and vinegar in another bowl. Beat wet ingredients into dry ingredients with electric mixer at low speed until combined. Add additional water by tablespoons until batter is smooth and thick. Beat 5 minutes on medium and occasionally scraping bowl.
Transfer pizza to pans to desired thickness. Bake 8-12 minutes or until crusts are lightly browned. Top with desired toppings.