Total Calories: 3,480
In a 2-quart saucepan, mix sugar, water and corn syrup. Stirring constantly over medium heat, bring to a boil. Place candy thermometer in mixture, being sure bulb is covered with syrup but not touching bottom of pan. Stirring occasionally, cook until temperature reaches 238° or until a small amount of mixture dropped in cold water forms a soft ball that flattens when removed from water. Remove from heat.
Stir in marshmallows and peppermint extract until marshmallows are melted. Stir in nuts until well coated. Transfer mixture to a piece of waxed paper. With two forks, spread mixture while still warm, (Mixture will be sticky.) Cool overnight or until set. Store in a tightly covered container.
High Altitude Adjustments: Since water boils and evaporates at a lower temperature than at sea level which affects the concentration of the candy mixture, use a good quality candy thermometer. Check the boiling temperature of water each time you intend to make candy. Immerse the thermometer bulb in a saucepan of water, bring to a boil and boil for several minutes. If the temperature reads more or less than 212° F, you will have to adjust the cooking temperature up or down by that much. For example, if the temperature of the boiling water is 206° F, you will have to reduce the temperatures called for in your recipes by 6°.