Step 1

In a large bowl and using a flexible spatula or whisk, stir the pastry cream until it resembles a creamy paste.

Step 2

In the bowl of a stand mixer fitted with the whisk attachment, whisk heavy cream on medium-high speed until fluffy and thick, about 2 to 3 minutes. (Alternatively, in a medium mixing bowl, whisk heavy cream by hand until thick peaks form).

Step 3

Using a flexible spatula, stir about one-quarter of the whipped cream into the pastry cream until it's completely incorporated, to lighten it. Gently but thoroughly fold in the remaining whipped cream, taking care not to deflate the mixture, until no visible whipped cream remains and mixture is homogeneous. Use immediately.