Basic Pastry Cream

In a saucepan, warm the milk over low heat until it starts to simmer. Reserve

In a bowl, mix together the cornstarch, flour, and salt

Gradually add the hot milk, stirring well, until a smooth mixture forms

Transfer back to the saucepan, add the egg yolks, and cook over low heat, stirring constantly, for 10 minutes or until thickened, without letting it boil so it doesn't curdle

Remove from heat and stir in the vanilla extract

Let it cool in a bowl, covered with plastic wrap stuck to the surface to prevent skin formation.