Using a large mixing bowl combine the warm water with the yeast and stir until the yeast dissolves.
In a separate medium-sized mixing bowl combine the butter, milk and salt, stirring until combined.
When both bowls have returned to room temperature, combine pour the butter, milk and salt mix into the bowl with the yeast and water. Add the flour and stir well.
Cover the mixing bowl in cling film and then allow it to sit overnight (it should almost triple in size in this time).
Add eggs and baking soda to the bowl and mix well, it doesn’t matter if the batter has a few lumps in it.
Turn the waffle iron on to a medium heat and grease it with butter. When the butter has started to sizzle you will be ready to add the waffle batter. Spoon the batter into the waffle iron and cook until the edges are firm and crispy and the waffle has turned golden brown.
Repeat these steps until you have used up all of the batter in the bowl.
Enjoy the waffles together with your favorite toppings.