Use to top Mini Banana Splits.
Combine sugar and 1/4 cup water in a small saucepan over medium-high heat. Bring to a boil without stirring. Wipe down sides of pan with a pastry brush dipped in water to prevent sugar crystals from forming. Just as liquid begins to brown, swirl pan to color evenly. Remove from heat when liquid is dark amber. Slowly add cream, stirring with a wooden spoon. Add butter and vanilla; stir to combine. Let cool slightly.
Be careful when adding cream to the caramel; the mixture will bubble vigorously and emit hot steam.