Gather all your ingredients. If toasting pistachios, spread on a baking sheet and bake at 350°F (175°C) for 5-7 minutes until fragrant.

In a medium saucepan, melt 4 tablespoons of butter over low heat. Add 4 cups of mini marshmallows, stirring until smooth and fully melted, about 5-7 minutes.

Remove from heat and fold in 6 cups of Rice Krispies and cooled pistachios. Combine gently until evenly coated.

Grease a 9x13-inch baking dish with cooking spray or butter. Transfer mixture to the pan and press down lightly into an even layer. Cool for 10-15 minutes.

Melt 1 cup of chocolate in a microwave-safe bowl in 30-second intervals, stirring until smooth. Drizzle over the cooled mixture.

Let the chocolate-coated treats cool completely at room temperature, about 30 minutes. Once set, cut into squares or rectangles.