For the perfect consistency - thick but pourable - serve this sauce slightly warm.
In a large skillet, melt butter over low heat. Add sugars and corn syrup. Using medium heat, bring mixture to a boil; cook about 2 minutes. Remove from heat; slowly stir in heavy cream. Allow to cool slightly, and serve (or store in an airtight container, refrigerated, up to 1 week, and warm before serving).