Procedure

1. In a heavy saucepan or kettle, dissolve the sugar in the milk and bring just to a boil.
2. With a whip, beat the egg yolks and whole eggs in a stainless-steel bowl.
3. Sift the cornstarch and sugar into the eggs. Beat with the whip until perfectly smooth.
4. Temper the egg mixture by slowly beating in the hot milk in a thin stream.
5. Return the mixture to the heat and bring to a boil, stirring constantly.
6. When the mixture comes to a boil and thickens, remove from the heat.
7. Stir in the butter and vanilla. Mix until the butter is melted and completely blended in.
8. Pour out into a clean, sanitized hotel pan or other shallow pan. Cover with plastic film placed directly in contact with the surface of the cream to prevent a crust from forming. Cool and chill as quickly as possible.
9. For filling pastries such as éclairs and napoleons, whip the chilled pastry cream until smooth before using.