Chocolate Pastry Cream

Instructions

1. In a medium saucepan, combine the milk and heat over medium heat until steaming, with small bubbles around the edge, about 4 minutes.
2. Meanwhile, in a medium heatproof bowl, whisk the egg yolks, sugar, cornstarch, cocoa powder, and salt until smooth and pale, about 1 minute.
3. Slowly pour about half of the hot milk into the yolk mixture while whisking constantly, then whisk everything back into the saucepan.
4. Cook over medium heat, whisking constantly and reaching into the corners of the pan, until the custard thickens and begins to bubble. Keep whisking for 1 minute more so the cornstarch thickens fully and the custard reaches at least 160°F.
5. Remove from the heat and whisk in the butter and dark chocolate until smooth. Strain through a fine-mesh sieve into a clean bowl.
6. Press plastic wrap directly onto the surface and refrigerate until cold and set, at least 2 hours.
7. Whisk the chilled custard briefly until smooth and creamy.
8. Spoon the filling into a piping bag fitted with a long filling tip. Poke a small hole in the side of each cooled doughnut and pipe in about 2 tablespoons, until the doughnut feels heavy.