1. Gradually whisk together half-and-half and flour in a saucepan over low heat. Cook, whisking constantly, 5 minutes or until a thick paste forms. Remove from heat; cool. Cover and chill 1 hour or until cold.
2. Beat paste, butter, and salt at medium speed with an electric mixer. Gradually add sugar; beat until light and fluffy. Stir in extracts.
Note: Superfine sugar has a light, powdery texture. Look for it at the supermarket in the baking area.