Makes about 4 cups
Diplomat Cream, a blend of pastry cream and whipped cream, can be used as a filling for cream puffs or chocolate éclairs, or as a layer in a trifle or icebox cake. The pastries should be baked and cooled before you make the diplomat cream; once the ingredients for this filling are mixed, you should pipe or spoon it immediately.
Sprinkle the gelatin over the cold water in a small bowl and stir to break up any clumps. Let the gelatin soften in the water for about 2 minutes. Heat the softened gelatin over simmering water or in a microwave for about 20 seconds on low power until the granules melt and the mixture is clear. Stir the gelatin into the pastry cream by hand with a rubber spatula until evenly blended.
Meanwhile, whip the heavy cream in a chilled bowl until it holds a medium peak when the whisk is turned upright. Working by hand with a spatula, fold the whipped cream into the pastry cream in 2 or 3 additions, folding just until evenly blended. Use at once.