Chocolate Pastry Cream In medium saucepan combine milk and chocolate, bring to a simmer and stir until chocolate is melted and smooth. Combine sugar, flour, cornstarch and egg yolks in mixer bowl. Beat on high speed until thick and pale yellow about 2 minutes.
Gradually pour about 1/3 of the hot milk mixture into egg mixture, stirring to combine. Scrape the egg mixture back into the pan and cook whisking constantly, scraping the bottoms and corners of the pan to prevent scorching, over low to medium heat until the custard is thickened and begins to bubble.
Continue to cook whisking 45-60 seconds. Using a clean spatula, scrape the custard into a clean bowl. Stir in vanilla extract. Cover the surface with wax or parchment paper to prevent skin from forming. Let cool; refrigerate 20 minutes. Will keep refrigerated up to two days.