Make the pastry cream:

• Combine milk and sugar. In a medium saucepan, heat the milk with sugar and vanilla extract over medium heat until it comes to a simmer.
• Mix egg yolks, salt and cornstarch. In a separate bowl, whisk together the egg yolks, salt and cornstarch until well combined.
• Temper the eggs. Slowly pour about 1/2 of the hot milk into the egg mixture, whisking constantly to temper the eggs.
• Combine mixtures. Pour the tempered egg mixture back into the saucepan with the remaining milk, whisking constantly.
• Cook until thickened. Begin heating the custard base on medium heat while whisking vigorously. The mixture should start to thicken within 1-2 minutes. Once boiling, reduce the heat and continue cooking for an additional 1-2 minutes after the first bubbles appear.
• Add butter. Remove from the heat, add butter, stirring well until the butter is completely melted and incorporated.
• Chill overnight. Pour the custard into a bowl and cover with plastic wrap touching the surface of the custard. Let the pastry cream cool to room temperature. Place in the fridge overnight.

Make the whipped cream:

• Dissolve gelatin. In a small bowl, pour in the water and add the gelatin powder. Stir to combine and let the mixture sit for around 10 minutes to bloom. Microwave the bowl for 15 seconds to dissolve the gelatin, being careful not to let it boil. Set aside to cool.
• Add some heavy cream. Add 2 tablespoons of cold heavy whipping cream, mixing well, to temper the cooled gelatin mixture.
• Make the whipped cream. Beat 1 cup chilled heavy cream with powdered sugar to soft peaks. Add tempered gelatin and continue to beat until stiff peaks form. Be sure not to over-beat the cream.

Make the Diplomat Cream

• Combine pastry cream and whipped cream. Using a balloon whisk, whip the pastry cream until it achieves a smooth and creamy consistency. Gently fold the whipped cream in pastry cream until well combined. It’s important to be gentle and not over-mix.
• Chill the cream for 30 minutes in the fridge. Then mix briefly with your balloon whisk and use the cream.