I'm not sure, I had to stay in the car since it was one person per group and someone else went in to snag them. $45 minimum at $3.75 * 12 for the best donuts on earth.
https://www.ubereats.com/providence/food-delivery/pvdonuts/81LM6l1NSnywCbneklIfMw
https://www.amazon.co.uk/Doughnut-History-Heather-DeLancey-Hunwick/dp/1780234988
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I have this book. Its interesting about the history of doughnuts. Theres some recipes in it as well but no sort of mainstream recipe.