Caramel Ice Cream Sundaes

In medium saucepan, stir sugar and water. Bring to a boil over medium-high heat. Reduce heat to medium and cook, swirling pan occasionally, until syrup turns amber. Remove pan from heat and carefully add heavy cream (mixture will sputter); stir to combine. Return to heat and bring to a simmer, stirring to dissolve any hard bits of caramel. Remove pan from heat and let cool 5 minutes. Whisk in butter, vanilla, and salt. Let sauce cool.

Scoop ice creams into sundae dishes. Spoon caramel sauce over ice cream and garnish with nut brittle.