Sprinkle sugar into a large cast iron skillet.
Cook over medium heat, stirring constantly with a wooden spoon, until sugar melts and turns light brown.
Remove from heat; add butter, and stir until blended.
Return mixture to low heat; gradually add half and half to hot mixture, 1 tablespoon at a time, stirring constantly.
Continue to cook mixture over low heat, stirring constantly, 10 minutes or until mixture is thickened and creamy.
Serve sauce warm over ice cream or pound cake.