Start by gathering all your ingredients for the Pistachio Rice Krispies. Measure out 6 cups of Rice Krispies, 4 cups of mini marshmallows, and 4 tablespoons of butter. Set aside about 1 cup of shelled pistachios, and if desired, prepare some food coloring.

In a medium saucepan, combine the 4 tablespoons of butter and 4 cups of mini marshmallows over low to medium heat. Stir continuously for about 5 minutes until the mixture is completely melted and smooth.

Once your marshmallow mixture is smooth, remove it from the heat and stir in the 6 cups of Rice Krispies and 1 cup of pistachios. If using food coloring, add it now and mix until evenly distributed.

Prepare a greased 9x13-inch baking pan and pour the mixture into it, spreading it into an even layer.

Allow the Pistachio Rice Krispies to cool at room temperature for about 30 minutes, or place them in the refrigerator for 10-15 minutes.

While the treats cool, melt about 1 cup of chocolate in a microwave-safe bowl, stirring until smooth. Drizzle over the cooled treats.

Allow the chocolate to cool and set for about 20 minutes before cutting into squares and serving.