In a heavy-bottomed saucepan, melt the brown sugar over medium heat without stirring until it turns into a smooth, amber liquid.

Carefully whisk in the butter until fully combined, then slowly add the heavy cream, stirring until smooth. Remove from heat and let cool slightly.

In a large bowl, beat the softened butter until light and fluffy, about 3-5 minutes.

Gradually add the cooled caramel sauce, beating until fully incorporated.

Slowly add powdered sugar, one cup at a time, mixing on low speed, then increase to medium and beat until smooth and creamy.

If too thick, add a tablespoon of milk or cream; if too thin, add more powdered sugar until desired consistency is reached.