Put the egg yolks and sugar in a bowl, and mix with a whisk. Add the cornstarch and mix.

Heat the milk, turning off the heat right before it boils. Add 1/3 of the milk to the bowl, mix until even, add the rest of the milk, stir, then return to the pot.

Steadily mix for 2 minutes on medium heat to prevent scalding.

Adjust the heat while checking on the cream from time to time. When it thickens, remove from heat, and mix in the butter and vanilla essence.

Transfer to a large platter, wrap tightly with plastic wrap, then chill.

When making Totoro bread, allow to cool, then fill the pastry bags with the cream!