In a medium saucepan, melt butter on medium heat. Add sugars and 1/2 cup heavy cream. Continue whisking on medium heat until mixture comes to a boil (about 6-8 minutes). Reduce heat to medium low, whisking continuously, and boil for 3 more minutes until the temperature reaches 220°F. Add remaining 1/4 cup heavy cream and whisk until blended. Cook on medium low an additional two minutes. Remove from heat.

Pour mixture into a pint-sized mason jar and allow to cool at room temperature. Sauce will thicken as it cools. Refrigerate for up to two weeks. Reheat in microwave or bring to room temperature before use. Enjoy.