In a large bowl combine the flour, baking powder, cornstarch, and salt; whisk to combine. In another bowl whisk together the egg, sugar, milk, water, butter and vanilla. Whisk the egg mixture into the dry ingredients just until combined.
Spray each side of the waffle pan with nonstick spray. Pre-heat the Waffle Puff Pan on medium heat for 3 minutes (if you have an electric bubble waffle maker, plug it in and follow the machine’s directions). Pour in ¾ cup of waffle batter, making sure to fill all the bubbles. Flip the waffle maker over and cook for 3 minutes. Flip the waffle maker again and cook for another 2 to 4 minutes or until golden brown.
Remove with a fork and top with your favorite toppings, or mold into a cone shape while it's still warm, and fill with ice cream when it is cool.