1. Combine the first 5 ingredients, stirring well with a whisk. Place the mixture in the freezer can of a table-top ice-cream freezer, and freeze according to manufacturer's instructions. Spoon ice cream into a freezer-safe container; freeze for 1 hour or until firm.
2. Coat a sheet of parchment paper with cooking spray. Combine sugar, 1 tablespoon water, and corn syrup in a small, heavy saucepan; bring to a boil. Cook 7 minutes or until golden, without stirring. Remove from heat. Stir in nuts and butter. Quickly spread the sugar mixture in a thin, even layer over prepared parchment; cool completely. Chop brittle; serve over ice cream.