In a saucepan, add 360g of the milk. Add the butter cubes and warm them over low-medium heat until the butter has melted. Leave it to cool down to lukewarm, then pour it into a large bowl.

Add the yeast, sugar, salt, flour, and eggs and whisk them together until combined. It will be a bit lumpy, but that is fine. Cover the bowl with a lid or a plate and place it in the refrigerator overnight. For faster waffles, the waffle batter can also ferment on the bench for 2 hours or until doubled, though they won't be as flavorful.

Once fermented, stir the batter with a fork to deflate it. Add 2-4 Tbsp of milk to create a pourable cake batter consistency.

Heat the waffle iron. Once it is hot, pour in approximately ¼- ½ cup of batter per waffle; this will depend on the size of your waffle maker. Bake them for 3-4 minutes until deep golden brown and crispy.

Serve the waffles immediately to retain their crispiness.

The baked waffles can be frozen for future use and reheated in the toaster.