Maple-Meringue Doughnuts

Ingredients

• 2/3 cup whole milk, at room temperature
• 2 1/2 teaspoons active dry yeast (from 2 [1/4-ounce] envelopes)
• 3 1/2 cups all-purpose flour (about 28 ounces), plus more for work surface and baking sheet
• 1 1/3 cups granulated sugar, divided
• 3 large eggs
• 2 teaspoons kosher salt
• 7 tablespoons unsalted butter (3 1/2 ounces), cut into 1/2-inch pieces, softened
• Peanut oil or grapeseed oil, for frying
• 3/4 cup Grade A dark amber maple syrup
• 2 large egg whites
• 1/4 teaspoon kosher salt

Steps

1. Stir together milk and yeast in the bowl of a stand mixer fitted with the dough hook attachment. Let stand until yeast dissolves, about 1 minutes. Add flour, 1/3 cup sugar, eggs, and salt; beat on low speed until flour is completely incorporated, about 2 minutes. Continue beating until dough is smooth and sticky, 2 to 3 minutes. Add butter, a few pieces at a time, and beat until butter is completely incorporated and dough is soft and elastic (it will still be very sticky), 5 to 6 minutes. Remove dough from bowl; wrap dough tightly in plastic wrap. Refrigerate at least 6 hours or up to 15 hours.
2. Remove dough from refrigerator, and unwrap; roll dough out on a well-floured surface into a 10-inch square (about 1/2 inch thick). Using a 3 1/2-inch round cutter, cut out 10 doughnut rounds, re-rolling scrap dough as needed. (Discard remaining dough scraps.) Arrange doughnut rounds 1 inch apart on a lightly floured baking sheet. Cover baking sheet tightly with plastic wrap. Let doughnut rounds proof at room temperature until doubled in height, 2 to 3 hours. (Shaped doughnuts can also be chilled 12 to 15 hours before proofing.)
3. Place remaining 1 cup sugar in a small bowl; set aside. Pour oil into a Dutch oven to a depth of 21/2 inches; heat over medium to 375°F. Working in batches, add doughnuts (be careful not to crowd them); cook until golden brown and a thermometer inserted into doughnuts registers 200°F, 1 minute and 30 seconds to 2 minutes per side. Transfer doughnuts to a baking sheet lined with paper towels; let cool about 1 minute. Toss warm doughnuts, one at a time, in bowl of sugar to coat. Set aside on a baking sheet; let cool completely, 30 to 40 minutes.
4. During final 10 minutes of doughnut cooling time, make the maple meringue: Bring maple syrup to a boil in a small saucepan over high. Meanwhile, beat egg whites in a heatproof bowl with an electric mixer fitted with the whisk attachment on medium-high speed until soft peaks form, about 1 minute. With mixer running on medium-high speed, immediately and carefully drizzle boiling syrup down the side of the bowl. When all of the syrup has been added, increase mixer speed to high. Add salt; beat until mixture is light, fluffy, and cooled to room temperature, 3 to 4 minutes. Use immediately.
5. Using a 1/3-inch round piping tip, poke a 1/2-inch-deep hole into one side of each doughnut. Transfer maple meringue to a piping bag fitted with 1/3-inch round piping tip. Working with 1 doughnut at a time, insert piping tip into the pre-made doughnut hole; fill with about 1/3 cup maple meringue. Serve filled doughnuts immediately.