Melt butter in a heavy saucepan over low heat; whisk in flour until smooth. Cook, whisking constantly, 1 minute. Stir in brown sugar and corn syrup; cook, whisking constantly, 5 minutes. Remove from heat; cool 15 minutes. Gradually whisk in half-and-half.
Beat whipping cream at high speed with an electric mixer until soft peaks form; fold into caramel mixture.