3 tablespoons water
coffee ice cream
Stir sugar and water in heavy medium saucepan over medium heat until sugar dissolves. Increase heat; boil without stirring until syrup turns deep amber, occasionally brushing down sides with wet pastry brush and swirling pan, about 6 minutes. Remove from heat. Slowly mix in cream (sauce will bubble vigorously). Add butter; stir over medium-low heat until smooth. Add nuts. Cool slightly. (Can be made 1 day ahead. Cover; chill. Before continuing, stir over medium heat until warm.)
Spoon ice cream into bowls. Spoon warm sauce over and serve.