We spent a lot of time perfecting this doughnut. We wanted a cakey and light texture that wasn’t greasy — and we achieved it! The classic craggy edges add a pleasant texture and hold onto the sweet glaze. A combination of buttermilk and sour cream provides tang and richness. But the secret ingredient to the batter is vegetable oil. Surprisingly, it doesn’t weight the doughnuts down but makes them even more moist and tender.
Yield: 8 doughnuts and 8 holes; Special equipment: 3 1/4-inch round cutter and 1 1/4-inch round cutter; Cook’s Note: When measuring flour, we spoon it into a dry measuring cup and level off excess. (Scooping directly from the bag compacts the flour, resulting in dry baked goods.)
Whisk together the flour, granulated sugar, baking powder, 1 1/4 teaspoons of the salt and the nutmeg in a large bowl until completely combined. Whisk together 2/3 cup of the buttermilk, the sour cream, eggs, yolks, 1 tablespoon of the vanilla paste and the oil in a medium bowl until completely combined. Fold the wet ingredients to the dry ingredients just until a soft and sticky dough comes together (do not overwork).
Line a rimmed baking sheet with parchment paper and liberally dust with flour (about 1/3 cup).
Scrape the dough onto the prepared baking sheet. Dust your hands and the top of the dough with more flour, then gently pat the dough to 3/4-inch thick.
Working on the baking sheet, punch out as many rounds as you can with a 3 1/4-inch cutter. Then use a 1 1/4-inch cutter to punch out the centre of each round. Dip the cutters in flour before each cut to avoid sticking. Gather the dough scraps and gently re-roll without overworking the dough. Repeat cutting until all the dough has been used (you should have 8 doughnuts).
Set a wire rack inside a rimmed baking sheet and line a second rimmed baking sheet with several layers of paper towels. Fit a large heavy pot with a deep-fry thermometer and pour in oil to a depth of 3 inches. Heat over medium-high until the thermometer registers 375ºF.
Fry the doughnuts in batches until deep golden brown, about 2 minutes per side. Transfer to the wire rack and let cool slightly. Fry the doughnut holes until deep golden brown, about 90 seconds per side. Transfer to the wire rack and let drain for 1 minute. Then transfer to the paper-towel lined baking sheet to cool for 10 minutes before glazing. (This two-step process gets a lot more oil out of the doughnuts than using only one method.) Repeat with the remaining dough, making sure the oil returns to temperature between batches.
Whisk together the confectioners’ sugar, the remaining 6 tablespoons buttermilk, the remaining 1 teaspoon vanilla paste and 1/8 teaspoon salt in a medium bowl until the glaze is smooth and the consistency of honey; add more confectioners’ sugar or buttermilk if necessary.
Dip each doughnut into the glaze on one side (we like the craggy side, it has more texture for an appetizing appearance), letting the excess drip back into the bowl, then return it to the wire rack. Toss the doughnut holes in the glaze to coat completely and return to the wire rack. Let the glaze set for 10 minutes before serving.