16 oz all purpose flour (455 g), plus more for dusting
2 oz granulated sugar (55 g)
1 teaspoon kosher salt
1 ½ teaspoons instant yeast
1 large egg, room temperature
1 large egg yolk, room temperature
½ cup buttermilk (120 mL), plus 2 tablespoons
6 tablespoons milk
1 teaspoon vanilla extract
4 tablespoons unsalted butter, melted
nonstick cooking spray, for greasing
6 cups oil (1.4 L), for frying
Pastry Cream
2 cups whole milk (480 mL)
1 large egg
3 large egg yolks
½ cup sugar (100 g)
2 ½ tablespoons corn starch
1 pinch kosher salt
3 tablespoons unsalted butter, softened
1 tablespoon vanilla extract
1 teaspoon lemon juice
4 tablespoons rainbow sprinkles
Frosting
8 oz mascarpone cheese (225 g)
½ cup heavy cream (120 mL)
2 tablespoons granulated sugar
1 teaspoon vanilla extract
1 pinch kosher salt
2 tablespoons pitaya powder
1 cup rainbow sprinkles (120 g)
How to Make It
1. Step
Make the dough: In the bowl of a stand mixer fitted with the dough hook, combine the flour, sugar, salt, and yeast.
2. Step
In a liquid measuring cup, combine the egg, egg yolk, buttermilk, milk, vanilla, and melted butter.
3. Step
Turn the mixer to medium-low speed. Slowly pour in the wet ingredients, then mix for 4–6 minutes, until the dough is smooth and supple.
4. Step
Grease a large bowl and a spatula with nonstick spray. Use the spatula to scrape the dough into the greased bowl. Cover with plastic wrap and set somewhere warm to rise until doubled in size, about 2 hours.
5. Step
While the dough is rising, make the pastry cream: Add the milk to a medium saucepan and bring to a simmer over medium heat.
6. Step
Add the egg and egg yolks, sugar, cornstarch, and salt to a medium bowl. Whisk until smooth.
7. Step
Slowly add about ½ cup (120 ml) of the warm milk to the egg mixture, whisking constantly to increase the temperature gradually without cooking the eggs.
8. Step
Pour the egg mixture into the pot of milk and cook over medium heat, whisking constantly, until thickened, 2–3 minutes.
9. Step
Remove the pot from the heat and whisk in the butter, vanilla, and lemon juice.
10. Step
Strain the custard through a fine-mesh sieve into a medium bowl. Cover with plastic wrap, pressing directly against the surface of the custard to prevent a skin from forming. Let cool to room temperature for 30 minutes, then chill in the refrigerator until ready to use.
11. Step
Once the pastry cream has cooled, stir in the rainbow sprinkles. Transfer to a piping bag fitted with a small round metal tip.
12. Step
Line a baking sheet with parchment paper and grease with nonstick spray.
13. Step
Punch the dough down and turn out onto a lightly floured surface. Roll the dough out to ½-inch ( ¼ cm) thick. Using a 3-inch round cutter, punch out donuts without holes. Reroll the excess dough once to cut out more donuts. You should have 6–8 total.
14. Step
Transfer the donuts to the prepared baking sheet and cover with a kitchen towel. Set aside for 1–2 hours, until doubled in size.
15. Step
While donuts are rising, make the frosting: In a stand mixer fitted with the whisk attachment, combine the mascarpone, heavy cream, granulated sugar, vanilla, salt, and pitaya powder. Whip on medium speed until soft peaks form, 5 minutes.
16. Step
Heat the oil in a large pot over medium-high heat until it reaches 350°F (180°C).
17. Step
Working in batches, fry the donuts in the hot oil until golden brown, 2–3 minutes per side. Transfer to a wire rack to cool.
18. Step
Pipe the pastry cream into the center of each donut.
19. Step
Dip each donut in the frosting, then cover liberally with rainbow sprinkles.
