Overnight + 20 minutes
In a large bowl, whisk together water, yeast and sugar.
Allow to sit 5 minutes, until mixture begins to foam.
Add flour, half and half, butter, salt and vanilla to mixture, mixing until smooth.
Cover bowl with plastic wrap and sit on countertop at room temperature overnight.
The next morning, heat waffle iron when ready to cook.
Whisk eggs, baking powder and apple cider vinegar into the batter.
Spray waffle iron with nonstick baking spray, and cook waffles according to manufacturer's instructions.