Step 1

In a medium-sized saucepan, heat the milk just until boiling point.

Step 2

In the meantime, in a separate bowl, combine the egg yolks, egg, corn starch, sugar and salt using a whisk.

Step 3

Once the milk has reached scalding point, pour 2/3 of it to the egg mixture, in a slow and steady stream, whisking continuously so you don't cook the eggs. Once you tempered the egg mixture, return it to the saucepan with the remaining milk and continue cooking, whisking constantly, until it thickens.Cook for another 1-2 minutes to make sure there isn't any cornstarch aftertaste.

Step 4

When it's done, add in the vanilla and butter and whisk until everything is combined, silky and smooth.

Step 5

Strain the pastry cream to a clean bowl through a sieve, to get rid of any cooked egg bits and lumps. Cover with cling film (plastic wrap) touching the surface to prevent skin forming. Let it cool at room temperature for about an hour, then place it in the fridge to cool completely.

Step 6

Transfer the cold pastry cream to a mixing bowl (it will be stiff, gelatinous-like) and give it a mix with an electric hand mixer to make it creamy again.In a separate bowl, whisk the cold heavy cream to stiff peaks and add it to the pastry cream. Mix everything together at medium-high speed until fully combined and smooth.

Step 7

Place the creme diplomate in a disposable piping bag fitted with a piping nozzle to fill choux, eclairs, doughnuts or cake! :)