Generously butter a standard baking sheet. Set aside.
Combine sugar and corn syrup in a 2-quart glass casserole dish. Stir to blend, then microwave (on high power) uncovered for 4 minutes. Stir after 2 minutes.
Stir in pistachios and microwave for 3 to 5 minutes more (until mixture is light brown). Then stir in butter and vanilla, blending well. If pistachios are unprocessed and unsalted, add a pinch of kosher salt (optional). Microwave for 1 to 3 minutes more. The mixture will be very hot. Add baking soda, stirring until mixture is frothy (about 1 minute).
Pour mixture onto prepared baking sheet. Let stand for 30 to 60 minutes, until hard. Break into bite-sized pieces. Store in an airtight container for up to 3 days or in the refrigerator for up to 7 days.
Substitute pistachios for your favorite nuts (cashews!) or peanuts.
1 cup granulated sugar
1/2 cup white corn syrup
1 cup pistachios, shelled
1 teaspoon butter plus additional butter for baking sheet
1 teaspoon vanilla
1 teaspoon baking soda
pinch of kosher salt (optional)
Number of servings: 8
Cooking time: 12 minutes