Filled Berliner Doughnuts

Instructions

1. Warm 3/4 cup (180 ml) milk until lukewarm (about 100°F/38°C). In a large mixing bowl, combine the milk, 2 tsp instant yeast, and 1/3 cup (67 g) sugar. Let sit for 5 minutes until foamy.
2. Add 2 large eggs, 4 tbsp (56 g) softened butter, vanilla bean seeds scraped from 1 split vanilla bean, and 1/2 tsp salt to the yeast mixture. Stir to combine.
3. Gradually add 3 cups (360 g) all-purpose flour, mixing until a sticky dough forms. Turn dough out onto a floured surface and knead for about 8 minutes until smooth and elastic, adding flour as needed to prevent sticking but keeping dough soft.
4. Place dough in a lightly greased bowl, cover with a kitchen towel or plastic wrap, and proof at warm room temperature until doubled in size, about 90 minutes.
5. While dough is proofing, prepare the vanilla custard filling. In a medium saucepan, heat 1 cup (240 ml) whole milk with the scraped seeds of the reserved vanilla bean until just simmering.
6. In a separate bowl, whisk 3 egg yolks with 1/2 cup (100 g) sugar and 1/4 cup (32 g) cornstarch until smooth.
7. Slowly pour the hot milk into the egg mixture in a thin stream, whisking constantly to temper the eggs.
8. Return the mixture to the saucepan and cook over medium heat, whisking constantly until thickened and bubbling, about 3-5 minutes. Remove from heat and stir in 1 tsp vanilla extract and 2 tbsp (28 g) butter until smooth.
9. Transfer custard to a bowl, cover with plastic wrap pressed directly onto the surface to prevent skin formation, and chill until cold, about 60 minutes.
10. After dough has doubled, turn it out onto a floured surface and roll to about 1/2-inch thickness. Use a 3-inch cutter to cut rounds and place them on a baking sheet lined with parchment paper. Cover with towel and rest 10 minutes.
11. Heat neutral-flavored oil in a deep pot to 350°F (175°C). Fry doughnuts in batches, flipping halfway, until golden brown, about 1 to 1 1/2 minutes per side. Drain on paper towels and cool to warm but not hot.
12. Fill a piping bag fitted with a long narrow tip with chilled vanilla custard. Inject custard into the side center of each doughnut.
13. Dust filled doughnuts with powdered sugar before serving.