Place milk in a 1-quart glass measure. Microwave at HIGH 3 minutes.
Combine sugar and egg yolks in a medium bowl; stir with a whisk. Gradually add hot milk to egg mixture, stirring constantly with a whisk. Return milk mixture to glass measure. Microwave at HIGH 2 1/2 minutes, stirring after 1 1/2 minutes. Stir in vanilla. Cover; cool to room temperature. Serve over angel food cake.