Crème Pâtissière

Method

1. Before beginning, measure all the ingredients and position a fine-mesh strainer over a medium heatproof bowl.
2. In another medium heatproof bowl, whisk together the egg yolks, granulated sugar, cornstarch, and salt until smooth.
3. Heat the milk in a medium saucepan over medium heat until steaming but not boiling.
4. Slowly pour about 1 cup of the hot milk into the egg mixture while whisking constantly.
5. Pour the tempered egg mixture back into the saucepan.
6. Cook over medium heat, whisking constantly, until the pastry cream thickens and bubbles begin to break the surface. Once bubbling, continue cooking and whisking constantly for about 2 minutes to thoroughly cook the cornstarch.
7. Remove from the heat and add the butter and vanilla. Whisk until completely smooth.
8. Immediately pour the pastry cream through the fine-mesh strainer, pressing through with a flexible silicone spatula.
9. Leave the pastry cream in the bowl or transfer it to a quarter sheet pan to cool more quickly. Press plastic wrap directly against the surface and refrigerate until completely chilled.
10. Before using, briefly whisk the chilled pastry cream until smooth and creamy.

Storage

Refrigerate, with plastic wrap pressed directly against the surface, for up to 3 days. Pastry cream does not freeze well.
 

Flavoring Options

The following amounts are for one full batch of pastry cream:
 

• Chocolate: Whisk 3 ounces finely chopped bittersweet chocolate (85 g) into the hot pastry cream after straining.
• Coffee: Dissolve 2 teaspoons instant espresso powder (about 4 g) in the milk as it heats.
• Pistachio: Whisk ⅓ to ½ cup pure pistachio paste (90–120 g) into the warm pastry cream.
• Hazelnut: Whisk approximately ½ cup hazelnut praline paste (125 g) into the warm pastry cream.

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Crème Diplomate

Method

1. Before beginning the pastry cream, place the cold water in a small bowl. Sprinkle the gelatin evenly over the water and let it bloom for 5–10 minutes.
2. Prepare the Pastry Cream through Step 6 above.
3. Remove the saucepan from the heat. Immediately add the bloomed gelatin along with the butter and vanilla called for in the Pastry Cream recipe. Whisk until the gelatin is completely dissolved and the pastry cream is smooth.
4. Immediately pour the pastry cream through the prepared fine-mesh strainer, pressing it through with a flexible silicone spatula.
5. Leave the pastry cream in the bowl or transfer it to a quarter sheet pan to cool more quickly. Press plastic wrap directly against the surface and refrigerate for about 30 minutes to 1 hour, until the pastry cream is cooled but not completely firm.
6. Transfer the cooled pastry cream to a large bowl and whisk until smooth and creamy.
7. In a stand mixer fitted with the whisk attachment or with an electric hand mixer, whip the cold heavy cream and powdered sugar to medium peaks.
8. Whisk about one-third of the whipped cream into the pastry cream to lighten it. Using a flexible silicone spatula, gently fold in the remaining whipped cream until smooth, light, and evenly incorporated.
9. Use immediately or refrigerate for 30–60 minutes before piping for cleaner definition.

For the best texture, use within 2 days and keep refrigerated.

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Crème Mousseline

Method

1. Allow the pastry cream and butter to reach approximately the same temperature, ideally 68–72°F. 
2. Whisk the pastry cream by hand until smooth and creamy. 
3. In the bowl of a stand mixer fitted with the whisk attachment, beat the softened butter and powdered sugar on medium-high speed until very smooth, pale, and slightly aerated, about 2–3 minutes.
4. With the mixer running on medium speed, add the pastry cream in several additions, allowing each addition to become fully incorporated before adding the next.
5. Once all the pastry cream has been added, scrape down the bowl and whisk briefly until the mousseline is smooth, light, and uniform. Use immediately. 

Storage

Refrigerate in an airtight container for up to 3 days from the day the pastry cream was prepared. Before using, allow the mousseline to soften to approximately 68–72°F and rewhip briefly until smooth.

Troubleshooting the Mousseline 
If it looks curdled or separated: The mixture is probably too cold. To bring it back together, microwave about ½ cup of the mousseline in short bursts just until melted, then slowly beat it back into the remaining mixture. 

If it looks greasy or soupy: The mixture is probably too warm. Refrigerate for 10–15 minutes, then whip again until smooth.