6tablespoonsunsalted buttermelted and slightly cooled
⅓cupwhole milk
1cupmashed sweet potatoplain, canned or home-baked
1largeeggroom temperature
For the Maple Glaze
2cupspowdered sugarsifted
3tablespoonsreal maple syrupGrade A dark preferred
1-2tablespoonsmilkto thin
1pinchsalt
Instructions
Make the Donuts
Heat the oven to 350 degrees F and grease a standard donut pan thoroughly, including the center posts.
Whisk the flour, baking powder, cinnamon, and salt together in a medium bowl.
In a larger bowl, whisk the sugar, melted butter, and egg until smooth. Add the mashed sweet potato and milk and whisk until no orange streaks remain.
Fold the dry ingredients into the wet with a spatula until just combined. A few dry streaks are fine. Do not overmix.
Transfer the batter to a piping bag and fill each well about two-thirds full, keeping the center post clear.
Bake for 15 to 18 minutes, until the tops spring back when pressed lightly. Cool in the pan for 5 minutes, then turn out onto a wire rack and cool completely.
Glaze
Whisk the powdered sugar, maple syrup, salt, and 1 tablespoon of milk until smooth, adding more milk a teaspoon at a time until the glaze falls off the whisk in a slow ribbon.
Dip each cooled donut face down, twist gently, and lift straight up. Return to the rack and let the glaze set for 15 to 20 minutes.
Notes
Cool completely before glazing: A warm donut melts the glaze into a thin, transparent film.
Real maple syrup only: Maple extract tastes like candy. Grade A dark syrup has the flavor to stand up to the sweet potato.
Sweet potato: Use plain puree or mash, never the canned kind packed in syrup.
Storage: Airtight at room temperature for 3 days, or freeze unglazed for up to 2 months and glaze after thawing.
Do not make the batter ahead: The baking powder activates on contact with liquid and the donuts bake up flat.