Put the warm water into a very large bowl, and sprinkle the yeast over top. Wait 5 minutes for the yeast to dissolve.
Combine the warmed milk and melted butter, and then add these to the bowl. Add the flour, sugar, and salt, and whisk well to combine until there are no lumps.
Cover with plastic wrap and let sit overnight at room temperature. (Or, if you’re having breakfast for dinner, just make this in the morning and let it sit all day!)
When you’re ready to make the waffles, first preheat your waffle iron. Then add the eggs, baking soda, cinnamon, and vanilla, and whisk well to combine. Make waffles however you normally do, and enjoy!
TIP: These waffles are absolute perfection hot off the iron. If you’re making a whole batch so that everyone gets served at once, keep cooked waffles on a rack in a warm oven until ready to serve.