Punch the dough down and roll out on a lightly floured surface to 1/2-inch thick. Use a 3-inch cutter to cut the donuts. Place the donuts on a floured parchment-lined baking sheet, cover with plastic wrap, and let proof for 15 minutes.
For the pastry cream, add the sugar, cornstarch, and milk to a large saucepan and mix until smooth. Cook, stirring continuously, over medium heat until mixture begins to thicken and boil. Reduce heat to medium and simmer for 1 minute.
Add a little bit of mixture to the egg yolks and whisk together, then add egg mixture to milk mixture. Place the saucepan back on the heat and bring to a light boil. Allow to boil for 2 minutes, stirring continuously.
For the chocolate glaze, heat the cream in a microwave or over the medium heat until just below boiling point. Pour the heated cream over the chocolate chips and let sit for 1 minute. Whisk it all together until the chocolate it fully melted.
Fill a piping bag with a round tip with the cream. Using a small knife, cut a hole in the side of each donut about 3/4 of the way into the donut and pipe a generous amount of vanilla cream into the center of the donut.