French Pastry Cream (Crème Mousseline)

Method

1. Split the vanilla bean lengthwise and add it to a saucepan with the milk. Heat over low heat until it reaches 90°C (194°F), then cover and let infuse for 20 minutes.
2. In a bowl, whisk the egg yolks with the sugar until the mixture becomes pale and fluffy.
3. Sift in the cornstarch and mix well until fully incorporated.
4. When the infused milk has cooled to about 50°C (122°F), gradually pour it into the egg mixture, stirring constantly with a spatula.
5. Return the mixture to the saucepan (including the vanilla bean). Cook over low heat, stirring frequently, until the cream reaches 82–85°C (180–185°F).
6. Remove from heat and continue stirring for 4–5 minutes. Add 125 g of cold butter and mix with an electric whisk until smooth and slightly frothy.
7. Transfer the cream to a bowl, cover with plastic wrap touching the surface, and refrigerate for 1 hour.
8. After 1 hour, remove the vanilla bean. Add the remaining 125 g of butter at room temperature (pomade consistency) and whip with an electric mixer until fully absorbed and creamy.