01 -
Combine all-purpose flour, granulated sugar, instant yeast, and salt in a large bowl. Add warm whole milk, egg, and softened butter, then knead the mixture until smooth and elastic, about 8 to 10 minutes. Cover the dough and allow to rise in a warm spot until doubled in size, about 1 hour.
02 -
Punch down the risen dough and roll out to approximately 1 inch thick on a lightly floured surface. Use a round cutter to cut out rounds. Arrange on a tray, cover lightly, and let rise again until puffy, approximately 30 to 40 minutes.
03 -
Heat oil in a deep pan to 340°F. Fry doughnuts in batches, turning as necessary, until both sides are golden brown. Remove and drain excess oil on paper towels. Allow to cool slightly.
04 -
Warm whole milk in a saucepan over medium heat. In a separate bowl, whisk together granulated sugar, cornstarch, and egg yolks until smooth. Gradually stream the warm milk into the egg mixture while whisking continuously, then pour the mixture back into the saucepan. Cook over medium heat, stirring constantly, until thickened. Remove from heat, add butter and vanilla extract, and stir until fully incorporated. Allow custard to cool completely.
05 -
Transfer the cooled custard into a piping bag. Using a small knife, make a hole in each cooled doughnut and pipe the custard filling into the center until well-filled.
06 -
Dust the filled doughnuts generously with powdered sugar and serve fresh.