Line a baking sheet with foil. Butter the foil, and set aside. In a heavy 20 cm skillet, combine nuts, sugar, and butter. Cook over medium heat, stirring constantly, for 9 minutes or till sugar melts and turns a rich brown color. Watch out for splatters. Remove from heat. Immediately stir in vanilla. Spread mixture onto the baking sheet. Cool completely. Break into small clusters. Store tightly covered. Makes 2.75 cups. From Better Homes and Gardens.