1) Put the milk (or milk and cream) in a medium saucepan and scrape in the vanilla bean seeds. Add the vanilla bean pod to the pot as well. Bring to a boil, remove from the heat, and allow to steep for 15 minutes. Discard the bean pod.

2) Meanwhile, whisk together the eggs (or yolks), sugar, cornstarch, and salt in a heatproof bowl until very smooth. For Rich Pastry Cream, the mixture will be very thick and will need extra whisking; set aside. Reheat the milk if it has become tepid.

3) Drizzle about one-quarter of the warm milk (or milk-cream mixture) over the egg mixture, whisking gently. Add the remaining warm milk (or milk-cream) and whisk to combine. Immediately pour the mixture back into the saucepan, and cook over medium-low heat until it begins to simmer and bubbles appear. Cook, whisking constantly to prevent scorching, for about 1 minute. The pastry cream should be thick enough to mound when dropped from a spoon, but still satiny. Remove from the heat and whisk in the butter and vanilla extract.

4) Allow the pastry cream to cool, stirring occasionally to release the heat. When almost at room temperature, scrape into an airtight container, press plastic wrap directly onto the surface, snap on the cover, and refrigerate for at least 4 hours or until thoroughly chilled. Refrigerate for up to 3 days.

Liqueur Variation:

For either Pastry Cream, 2 tablespoons of liqueur, such as Cointreau, rum, eau de vie, Kahlua, or the liqueur of your choice may be gently stirred into the pastry cream during the cooling phase at the end of the recipe.