2 cups all-purpose flour
1/2 cup cornstarch
1/2 cup cold water
1 teaspoon baking powder
1 teaspoon baking soda
1 teaspoon salt
1/2 teaspoon ground cinnamon
2 tablespoons butter, softened
2 cups white sugar
4 egg whites
3 egg yolks
Preheat oven to 375 degrees F (190 degrees C). Grease a 9x13-inch pan.
In a medium bowl, mix flour, cornstarch, cold water, baking powder, baking soda, salt, cinnamon, and butter. Stir into the hot water mixture until thoroughly combined. Mix in sugar, egg whites, egg yolks, and flour mixture. Pour mixture into prepared pan.
Bake at 375 degrees F (190 degrees C) for 30 minutes in the preheated oven, or until a toothpick inserted into the center of the pie comes out clean. Cool before removing from pan.