Pastry Cream

Put 2 cups milk over medium heat and bring to a frothy (not boiling) scald. Meanwhile, heat a skillet full of water. Beat 2 egg yolks in a small bowl. In an enamel or steel bowl, whisk together 1/4 cup sugar and 2 T. cornstarch (or 3 T. flour). Pour the scalded milk into the flour mixture in a thin stream, whisking constantly. Place the bowl in the simmering water and stir till thickened, 5 minutes or so. Pour a cupful of the hot milk mixture into the egg yolks, whisking well, and pour back into the hot milk. Keep it in the simmering water, stirring constantly, until even more thickened, 5 minutes or so. Remove from heat and stir in 2 T. butter and 2 tsp. vanilla. Chill with tinfoil or a plastic bag pressed directly against its surface.