Old-Fashioned Buttermilk Bar Doughnuts

Makes: 30 doughnuts

For the doughnuts

4 tablespoons (1/4 cup) unsalted butter

3 1/2 cups all-purpose flour, plus more for dusting

2 teaspoons baking powder

1 teaspoon kosher salt

3/4 teaspoon ground nutmeg

1/4 teaspoon baking soda

1/2 cup packed light brown sugar

1/2 cup granulated sugar

1 tablespoon vanilla extract

2 large eggs

1 large egg yolk

3/4 cup buttermilk

2 to 3 quarts vegetable oil, for deep frying

For the vanilla glaze

2 1/2 cups powdered sugar, sifted if lumpy

1/4 cup water, plus more as needed

1 tablespoon vanilla extract

Make the doughnuts

1. Place 4 tablespoons unsalted butter in a small microwave-safe bowl. Microwave on high until melted. Set aside to cool slightly.

2. Place 3 1/2 cups all-purpose flour, 2 teaspoons baking powder, 1 teaspoon kosher salt, 3/4 teaspoon ground nutmeg and 1/4 teaspoon baking soda in a medium bowl and whisk to combine.

3. Place the melted butter, 1/2 cup packed light brown sugar, 1/2 cup granulated sugar and 1 tablespoon vanilla extract in bowl of a stand mixer fitted with paddle attachment. (Or use a large bowl and electric hand mixer.) Beat on medium speed until combined, scraping bowl with flexible spatula as needed, about 2 minutes.

4. Reduce the speed to low. Add two large eggs and one large egg yolk one at a time, stopping and scraping down the bowl as needed. Add 3/4 cup buttermilk and mix until just combined.

5. Add the flour mixture all at once and mix on the lowest speed just until a few streaks of flour remain. Remove the bowl and continue mixing by hand until there are no dry bits of flour. The dough will be quite sticky. Refrigerate for at least 30 minutes and up to overnight so the dough is easier to work with: It remains sticky but firms up considerably.

6. Line two rimmed baking sheets with parchment paper and dust it with flour. Heavily flour a work surface and your hands with flour. Transfer half of the dough (about 18 ounces) to the work surface and sprinkle it with flour. Pat the dough into a 3-by-24-inch rectangle with a long side closer to you, adding more flour to the work surface as needed.

7. Use a floured bench scraper or knife to cut the rectangle crosswise into 1 1/2-inch-by 3-inch bars, flouring underneath the bars, the work surface and the bench scraper as you work. Once all the bars are cut, dip the bench scraper in flour and very gently press it down the center of each bar lengthwise, going as far down as you can without cutting it in half. (This will give your doughnut an indentation for the quintessential buttermilk bar look.)

8. Using a brush, gently brush the excess flour off the bars. Use the floured bench scraper or thin metal spatula to gently transfer each bar to one of the baking sheets, flipping it over so that it is indentation-side down. Brush the excess flour from the other side of the bars. Refrigerate and repeat with shaping and cutting the remaining dough.

9. Fill a large, heavy-bottomed pot or Dutch oven with about 2 inches vegetable oil. Heat the oil on medium-high heat until 370 degrees. Meanwhile, fit a wire rack over a baking sheet.

10. Remove the first tray of bars from the refrigerator. Frying in batches of 6 to 8 so as not to crowd the pot, use the bench scraper to carefully transfer the doughnuts into the hot oil one at a time. Fry, adjusting the heat as needed to maintain a temperature of 360 to 365 degrees, until golden brown, about 1 1/2 minutes per side. Carefully transfer the doughnuts to the rack with a slotted spoon or spider, letting the excess oil run off as you remove it from the pot. Repeat frying the remaining doughnuts, heating the oil to 370 degrees before each batch. Let cool completely before glazing.

Make the glaze

1. Place 2 1/2 cups powdered sugar, 1/4 cup water and 1 tablespoon vanilla extract in a large bowl and whisk until shiny and smooth. If the glaze is too thick to run off a spoon easily, whisk in more water a teaspoon at a time.

2. Dip a doughnut indentation-side down halfway into the glaze. Lift it up and allow the excess glaze to drip back into the bowl. Return to the rack glazed-side up and repeat with the remaining doughnuts. Let sit until the glaze is set before serving.

Note: The doughnut dough can be made and refrigerated up to 24 hours before frying, and leftover doughnuts can be stored in an airtight container at room temperature for up to two days.