Melt your white frosting in the microwave at 30 second increments so it is runnier than normal.

Spread the white frosting over each cookie using the back of a spoon. Let some dribble over the edges for a "puddle" look.

Place marshmallows on a microwave safe plate, then heat in the microwave for 30 seconds. Watch the marshmallows as they cook and stop the microwave as soon as the marshmallows start to get puffy. Do not let them double in size.

Spray your fingers with cooking spray, and carefully pull the marshmallows off the plate by the base and set them on top of the frosted cookies.

Decorate as you'd like with the colored frosting.

Serve and enjoy!