In a small saucepan over low heat, stir the butter with the milk until just melted. Remove from heat and stir in the yeast do dissolve, milk should be warm to the touch, but not scalding. Let sit for 10 minutes.
In a large bowl, combine all of the ingredients and stir until combined. Don’t worry about it being smooth and perfect, a few lumps are totally ok.
Cover with plastic wrap and let rest for at least 1 hour. Mixture will grow and begin to bubble. *At this point you can refrigerate the batter overnight.
When ready to cook, preheat your waffle iron. Spray with cooking spray and pour batter into iron. Be cautious not to over fill like I do every. single. time. Cook until waffle is golden brown and cooked through.