Instructions

1. Lightly coat an 8×8″ baking pan, preferably metal, with nonstick vegetable oil spray, or aluminum foil.
2. Heat ¼ cup granulated sugar, ½ cup light corn syrup, and 1 tsp salt in a large saucepan over medium, stirring often, just until sugar is dissolved and mixture is simmering, about 3 minutes. (Do not bring to a rapid boil.) Reduce heat to low, add ⅔ cup pistachio cream or pistachio butter, and mix until pistachio cream is melted and mixture is combined. Stir in a few drops of green food coloring to enhance the green if desired.
3. Immediately add 3 cups puffed rice cereal; mix gently to coat. Scrape into prepared pan (try to plop it down over entire bottom, not just in the center) and very gently press into a flat, even layer with oiled hands or flat-bottomed measuring cup, taking care not to smash or compress too much. (Pressing too hard can result in dense, overly chewy bars.) Set aside.
4. Microwave 4 oz. semisweet chocolate and ½ tsp salt in a microwave-safe bowl on high in 15-second bursts, stirring after each, until chocolate is melted, about 30 seconds total. Pour chocolate over the bars and, working quickly, spread into a thin, even layer with an offset spatula. Sprinkle ¼ cup finely chopped salted roasted pistachios on top; press in slightly to adhere. Let sit at room temperature at least 2 hours to allow chocolate to set. (Or, chill 45 minutes to speed up the process.)
5. Using foil paper, pull the bars out of pan, and transfer to a cutting board to cut into bars.
6. Bars can be made 4 days ahead. Store airtight at room temperature.