Combine all ingredients except for chocolate chips: brownie mix, vegetable oil, egg, water. Mix well.
Fold in chips after mixture is blended.
Drop by uniform teaspoons onto parchment lined baking sheet and bake for 7 to 8 minutes. Allow to cool on sheet for about 5 minutes. Then cool completely on rack.
Using a regular table knife, spread a liberal amount of frosting onto the underside of 1 cookie. Find another cookie similar in size and shape and press gently onto frosting, bottom side down. Wiggle slightly to set. Continue until all cookies are used.
Store in refrigerator overnight to allow frosting to firm slightly.
Allow to sit at room temperature for about 10 minutes before eating.