Vanilla Pistachio Pastry Cream

Instructions

1. Set a fine-mesh sieve over a clean heatproof bowl and keep it beside the stove.
2. Warm the milk with the split and scraped vanilla bean in a saucepan over medium heat until it is steaming and small bubbles appear around the edge. Do not let it boil hard. The milk should be hot enough to steam steadily but not scorch on the bottom.
3. While the milk heats, whisk the sugar, cornstarch, salt, and egg yolks in a bowl until smooth and slightly lighter in color. There should be no visible pockets of dry cornstarch.
4. Slowly whisk about half of the hot milk into the yolk mixture, then pour the tempered mixture back into the saucepan while whisking. Adding the hot milk gradually keeps the eggs from scrambling.
5. Cook over medium heat, whisking constantly, until the cream thickens and bubbles break through the center. Continue cooking for 1 minute, still whisking; if you check with a thermometer, the cream should reach at least 165°F (74°C). The pastry cream should look glossy, thick, and hold the tracks of the whisk for a moment.
6. Press the hot pastry cream through the sieve, removing the vanilla pod if present. Stir in the pistachio paste until the cream is completely smooth; if using vanilla extract or paste, stir it in at this stage. The finished cream should be glossy and uniform in color, with no oily streaks or visible lumps.
7. Transfer the pastry cream to a shallow heatproof container, press parchment or plastic wrap directly onto the surface, and refrigerate promptly until thoroughly cold, at least 3 hours. Whisk briefly before piping or spreading if the chilled cream feels very firm.