Strawberries with Champagne Sauce

2 egg yolks
1/2 cup granulated sugar
2 teaspoons cornstarch
1 cup milk
1 teaspoon vanilla extract
1/2 cup whipping cream, stiffly beaten
1/4 cup champagne
1 quart strawberries, washed and thoroughly drained

Combine yolks, sugar and cornstarch. Add milk slowly, stirring constantly. Cook over medium heat until sauce coats a wooden spoon. Refrigerate until cool. Add vanilla extract, then fold in whipping cream. Gently fold in champagne, then serve over strawberries.