Preheat the oven to 200 degrees C. Grease a 23cm square baking tin.
Whisk together the eggs, water and oil in a bowl until evenly blended then set aside. Stir together the cornmeal, millet flour, rice flour, sugar, baking powder and salt in a separate large bowl, then make a well in the centre. Pour the egg mixture into the well and stir just until combined. Pour the mixture into the prepared tin.
Bake in the preheated oven until golden and the top springs back when lightly pressed, about 20 minutes.
Add 1 teaspoon of xanthan gum to the mix for great results. You can also add a spoonful of honey for added sweetness.