In a bowl mix together the cake mix, oil and eggs. Do this by hand as it is very stiff. You are looking for everything to just come together to form a dough.
Roll dough into 1 balls. Place about 2 apart on an ungreased cookie sheet.
Note: if dough is too sticky to roll into balls easily, refrigerate for a short time.
Bake cookies 8 to 11 minutes at 350. Cookies should still be soft but the tops will have a cracked appearance when done.
Remove cookies from baking sheets to cool.
Allow to cool completely.
Choose 2 cookies that are the same size and shape. Place about 1/2 to 1 teaspoon of frosting on the bottom of one cookie. Put the two cookies together bottoms facing each other to form the sandwich.
Note: I like to use the following combinations, but feel free to experiment. Chocolate cookie with fudge frosting, chocolate cookie with vanilla frosting, white cake with vanilla frosting (add about 1/2 teaspoon of almond extract to the frosting), carrot cake cookies with chream cheese frosting, funfetti cookies with rainbow chip frosting (kids love this one for the colors).