Bring the heavy cream to a full boil in a medium saucepan over medium-high heat, then continue to boil rapidly for 45 to 50 minutes, until thickened like a white sauce, stirring occasionally.
Off the heat, add the Gorgonzola, Parmesan, salt, pepper, and parsley. Whisk rapidly until the cheeses melt and serve warm. If you must reheat, warm the sauce over low heat until melted, then whisk vigorously until the sauce comes together.
