Preheat a waffle iron to the highest temperature possible.
In a large mixing bowl, whisk the flour, cornmeal, cornstarch, sugar, baking powder, baking soda, salt, pepper, and garlic powder together. Whisk in the eggs, melted butter, and milk. Allow the batter to rest reserving the seltzer water for later.
Meanwhile, chop and prep all the quesadilla fillings.
When you are ready to start cooking, whisk the seltzer water into the waffle batter. Spray the hot waffle iron with nonstick cooking spray.
Ladle the waffle batter onto the hot iron. Use enough batter to cover the waffle iron without spilling over the edges, usually around 1/3 cup.
Sprinkle diced onions and peppers over the waffle batter and close the waffle iron. Rotate the waffle iron (if your waffle maker offers that option) and cook for approximately 2 minutes, until lightly golden.
Open the waffle maker and sprinkle shredded chicken, cheese, and pico de gallo over half of the waffle. Use wooden tongs to fold the other half of the waffle over the top of the fillings and close the waffle iron again. Cook again for 2-3 minutes to heat the fillings and crisp up the edges.
Carefully lift out of the waffle maker and serve while hot, with guacamole and sour cream if desired. Repeat with the remaining ingredients.
NOTES: If you want to serve all your Waffle Iron Quesadillas at the same time, heat the oven to 200 degrees F, and keep the quesadillas warm inside the oven as you finish cooking the rest.