Prepare the batter and refrigerate at least 8 hours before baking--all day to have waffles for dinner (try over under ice cream), OR overnight to have them for breakfast.
Make the batter in the morning OR evening:
Combine and whisk together the dry ingredients in a large bowl: flour, yeast, sugar and salt. Combine the melted butter and milk (or buttermilk). Add the mixture to the dry ingredients. Whisk eggs and vanilla together in a separate small bowl. Add the egg-vanilla mixture to the other mixture, and whisk until well-combined. Cover with plastic wrap and stick in the fridge until tomorrow morning.
That evening OR following morning:
Prepare waffle iron as usual. Stir the batter to deflate it (it should be puffy and frothy). Add to waffle iron the same way you would other batter, keeping in mind that this batter will rise more than batters that use baking powder instead of yeast.
Makes 4-6 large round waffles.
NOTE: This recipe is easily made with milk OR buttermilk.