Soak the gelatin in cold water to soften, then drain and set aside. In a saucepan, bring the milk and half the sugar to a boil. In a separate bowl, gently whisk together the egg yolks, the remaining sugar, vanilla, and powders until smooth. Gradually temper the egg yolk mixture by slowly adding the hot milk while whisking constantly. Pour the tempered mixture back into the saucepan and bring it to a boil. Cook for 2 minutes, whisking constantly, until thickened. Remove from heat and immediately stir in the softened gelatin until fully dissolved. Spread the custard onto a frozen baking tray lined with plastic film. Cover the surface of the custard with plastic wrap to prevent a skin from forming. Refrigerate until fully chilled.Once chilled, beat the pastry cream until smooth before using for piping.