Step 1

Heat oven to 350°F. Line 8-inch square pan with foil, extending over edges.

Step 2

In medium bowl, break up cookie dough. Add baking cocoa; mix with spoon, or knead with hands until well blended (dough will be stiff). Press evenly in bottom of pan.

Step 3

Bake 15 to 20 minutes or until edges are set (do not overbake). Cool completely on cooling rack, about 1 hour.

Step 4

In medium microwaveable bowl, microwave chocolate chips and whipping cream uncovered on High 1 minute, stirring after 30 seconds; stir until chips are melted and mixture is smooth. Spread chocolate mixture evenly over cooled cookie base. Sprinkle with miniature marshmallows, slightly pressing into chocolate.

Step 5

Refrigerate about 30 minutes or until chocolate is set. For bars, cut into 4 rows by 3 rows; cut each bar in half diagonally for a total of 24 triangular bars. Store covered in refrigerator.