Place a medium bowl in a larger bowl of ice water. Set Aside. Bring milk to the boiling point in a heavy saucepan over medium heat. Meanwhile, beat egg yolks in a large mixer bowl until smooth. Gradually add 1/3 cup plus 1 tablespoon of sugar and continue berating until the mixture is pale yellow and forms a ribbon when beaters are lifted (about 7 minutes.) Gradually add boiling milk to yolk mixture, beating constantly to avoid the yolk curdling. Return the mixture to the saucepan, and cook over low heat stirring with a wooden spoon, for 30 seconds. Immediately pour custard into the bowl set over ice water. Cool, stirring occasionally. Beat the butter and praline paste in a large bowl until smooth and creamy. Gradually beat in cooled custard.