I experimented with making bubble waffles in a regular waffle iron, and they turned out much better than I expected. No, they do not look like bubble waffles, but yes, they taste just like them.
In a large bowl, combine whisk together the flour, tapioca starch, baking powder, and custard powder
In a medium bowl, combine the eggs and sugar. Use a whisk or hand mixer to beat the eggs until they are light and fluffy, about 2-3 minutes.
Stir in the milk, oil, and vanilla extract.
Now, add the dry ingredients to the wet ingredients and beat until smooth. Transfer the batter to the fridge and rest for at least one hour.
Grease both sides of the waffle iron with some oil. Pour enough batter in so that the bottom is completely filled (about 1 ¼ cups). Close the iron. Flip it upside down for 15 seconds, then flip it back. Cook until golden brown.
Transfer the waffle to a wire rack and it will crisp up as it cools. Enjoy!