Heat oven to 350°F. Line 8-inch square pan with foil, allowing overhang of 2 inches over sides of pan. Spray foil with cooking spray. Flatten and press cookie dough rounds evenly in bottom of pan. Bake 22 to 26 minutes or until set. Cool completely, at least 1 hour.

Using foil to lift, remove bar from pan, and peel foil away. In medium bowl, beat softened butter, powdered sugar and vanilla with spoon until smooth and spreadable. Tint with food color to desired color. Spread over top of bar. Cut into 4 rows by 3 rows.

In small microwavable bowl, microwave chocolate chips uncovered on High 30 to 60 seconds or until chips can be stirred smooth. Spoon melted chocolate into small resealable food-storage plastic bag; partially seal bag. Cut off tiny bottom corner of bag. For each monster face, squeeze bag to pipe on top half of rectangle to look like hair; pipe zigzag mouth. Place 2 eyes under piped hair; press half of pretzel on each side of bar into frosting. (Use photo as guide.)

Let stand until chocolate is set, about 1 hour 30 minutes. Store in single layer covered in airtight container at room temperature.