70ml (or ¼ cup + 2 teaspoons) heavy whipping cream
16g (or 4 teaspoons) granulated sugar
Instructions
NOTE: can be made one day before you want to use it in a mousse. The mousse itself is best made 1 day before you plan on serving it.
To a small medium-sized bowl, add the cornstarch and about a tablespoon of the milk. Stir into a paste. If the paste is too dry, add a little more milk. At any rate, it’s always best to start with a small amount of milk and add more if needed, because adding the milk little by little ensures that the cornstarch dissolves evenly and that the resulting paste doesn’t have any lumps in it. Add the yolk and whisk until frothy.
Add the rest of the milk, the whipping cream and the sugar to a small saucepan. Heat over medium-high heat, stirring to dissolve the sugar. Once the sugar has dissolved, crank up the heat and bring the mixture to scalding point.
As soon as the first bubbles start to appear, take the saucepan off the heat. Slowly drizzle the hot milk mixture into the egg mixture, whisking continuously to prevent the yolk from curdling.
Once all the liquid has been added, return the mixture to the saucepan. Heat over medium-high heat, stirring continuously with a rubber spatula until the mixture thickens considerably and the first bubbles start to appear on the surface of the pastry cream.
Take the pan off the heat and, using a rubber spatula, scrape the pastry cream into a small, clean bowl. Press a piece of plastic wrap directly onto the surface of the pastry cream to prevent a skin from forming and leave to cool to room temperature before placing in the fridge until use.
Recipe by The Tough Cookie at https://thetoughcookie.com/building-blocks-2/plain-pastry-cream/