Preparation Simmer maple syrup and salt in heavy medium saucepan over medium heat until slightly thickened, about 5 minutes (do not stir). Add 1/2 cup ice cream and whisk until smooth, about 1 minute. Stir in walnuts. (Can be made 4 hours ahead. Cover and chill. Rewarm over low heat, stirring often.) Scoop remaining ice cream into bowls. Spoon sauce over and serve.
Preparation Simmer maple syrup and salt in heavy medium saucepan over medium heat until slightly thickened, about 5 minutes (do not stir). Add 1/2 cup ice cream and whisk until smooth, about 1 minute. Stir in walnuts. (Can be made 4 hours ahead. Cover and chill. Rewarm over low heat, stirring often.) Scoop remaining ice cream into bowls. Spoon sauce over and serve.