Step 1

Heat the milk. Add the milk to a medium saucepan. Heat milk over medium heat until it begins to simmer and bubbles appear around the edge of the saucepan. Do not boil the milk.

Step 2

Whisk eggs and sugar. Whilst the milk is heating, place the yolks and sugar in a medium-sized mixing bowl set on a tea towel and whisk until thickened and pale. Add in cornflour and cocoa powder and whisk until combined.

Step 3

Temper the eggs. While whisking the egg mixture continuously, pour in the milk in a slow thin stream and whisk until combined. Pour the mixture straight back into the saucepan and return to low heat.

Step 4

Heat the custard. Add in the chopped chocolate and whilst continuously whisking, (do not stop!), heat the custard on low to medium heat until it starts to bubble and thicken and the chocolate melts thoroughly. Once bubbles appear, heat for a further minute for the cornflour to reach the full point of thickening.

Step 5

Add in butter and cool pastry cream. Remove the pan from the heat and pass the mixture through a fine-mesh sieve set over a medium-sized bowl. This will remove any egg lumps. Add the butter to the custard and whisk until melted and combined and the cream is smooth and shiny.

Step 6

Chill the pastry cream. Cover the cream with plastic wrap and set aside until cooled to room temperature, then refrigerate for a minimum of 3 hours, preferably overnight. When ready to use, remove plastic wrap and whip or beat vigorously until smooth again.