Remove vanilla bean. Gradually pour about 1/3 of the hot milk into the egg mixture, stirring to combine.
Scrape the egg mixture back into the pan and cook, whisking constantly over low to medium heat, scraping the bottom and corners of the pan to prevent scorching, until the pastry cream is thickened and begins to bubble.
Continue to cook, whisking 45-60 seconds. Using a clean spatula, scrape the pastry cream into a clean bowl. If vanilla bean is not used, add 3/4 teaspoon Pure Vanilla Extract.
Cover the surface of the custard with waxed or parchment paper to prevent skin from forming. Let cool; refrigerate before using. Will keep refrigerated up to 2 days.