Melt butter in a heavy saucepan over low heat. Add flour; stir until smooth. Cook 1 minute, stirring constantly. Gradually add whipping cream; cook over medium heat, stirring constantly, until thickened. Stir in mustard and pepper. Add ham; stir well.
Spoon mixture into an oiled 3 1/2-cup mold. Cover and refrigerate at least 4 hours. Unmold onto a serving platter. Serve cold with crackers.