1 tablespoon butter
1/4 cup sweetened condensed milk
2 cups granulated sugar
2 tablespoons lemon juice
1/4 teaspoon salt
10-12 ounces white chocolate, coarsely chopped
1 teaspoon vanilla extract
1 cup pistachios, shelled and roasted
In 2-quart heavy saucepan sweetened condensed milk, sugar, salt, and lemon juice to a boil over medium heat. Continue to boil until it reaches 236 degrees F (soft-ball stage; about 20-30 minutes). Remove from heat, add butter and white chocolate (or white chips). Do not stir; let sit undisturbed until the pan can be handled (about 110 degrees F).
Stir until thick, fold in vanilla and pistachios. Spread into a buttered 8-inch square pan. Cool. Cut into 1-inch squares.
NOTE: 10 to 12 ounce package white (vanilla) chips can be substituted for 10 to 12 ounces of white chocolate. White chips bake well and are about 1/3 the price of white chocolate.