Ingredients
6 tablespoons unsalted butter, plus more for pan
1 bag (10 1/2 ounces) mini marshmallows
1/4 cup unsweetened Dutch-process cocoa (spooned and leveled)
6 cups crisp rice cereal
2 ounces bittersweet chocolate, melted
Preparation
Butter an 8-inch square baking pan. Line bottom and two sides with parchment paper, leaving a 2-inch overhang on both sides. Butter paper; set pan aside.
In a large saucepan, combine butter, marshmallows, and cocoa. Cook over medium, stirring frequently, until melted, about 6 minutes; stir in rice cereal. Press rice mixture into prepared pan; drizzle with melted chocolate. Let cool to room temperature; cut into 16 bars. (To store, keep in an airtight container at room temperature, up to 5 days.)