Scrape the seeds from <quantity>⅓</quantity> of a vanilla bean

Add <quantity>500<unit>ml</unit></quantity> of milk to a small pot and add the vanilla seeds. Bring to a simmer over low heat

Add <quantity>140<unit>g</unit></quantity> of sugar to a bowl together with <quantity>130<unit>g</unit></quantity> of egg yolk. Whisk to combine

Add <quantity>50<unit>g</unit></quantity> of cornstarch and whisk until there are no lumps

Pour half of the hot milk and whisk to combine

Return the mixture to the pot with the remaining ½ of the milk. Whisk over low heat until it begins to thicken. Stir with a spatula to get a thick and smooth cream

Spread the cream on a tray to cool down quickly

Cover with clingfilm in contact with the surface

Refrigerate until cool

Transfer the cream to the bowl of a stand mixer and beat with the whisk attachment on medium speed

Add <quantity>50<unit>g</unit></quantity> of butter and whisk until combined. The pastry cream is ready

Enjoy it in your desserts and pastries!