Preheat oven to 375 degrees F. Line 2 baking sheets with silicone baking mats or parchment paper.
In a large bowl, combine cake mix, melted butter, and eggs until smooth.
Use a cookie scoop to portion dough into 1-inch balls and place on your prepared baking sheets several inches apart. (These cookies spread a lot.)
Bake for 9-11 minutes or until set. (Cookies will puff up a bit in the oven and flatten as they cool.)
Remove from oven and cool on baking sheets for 2 minutes before transferring to a wire rack to cool completely.
Place frosting in a microwave-safe bowl and heat for 30 seconds. Stir frosting and check consistency; the frosting should flow off the spoon easily.
Drizzle frosting over the cookies (I like to use a criss-cross pattern) while cookies are still on the wire rack. (Extra frosting will fall through and not stick to the cookies.) Reheat the frosting as needed to get a good drizzle going.
Allow frosting to set before transfer to an airtight container to store. The frosting will be soft, but you can harden it up by placing the cookies in the fridge.