Prepare cake according to package directions. Before pouring batter into pan remove 2 teaspoons of crushed Oreos and put them into a separate bowl or resealable sandwich bag. Set bag aside. Fold remaining Oreos into batter. Pour batter into pan and continue to bake according to package directions. Cool completely.

When cake is cool, frost with frosting. Take remaining 2 teaspoons of Oreos and finely crush them. If in a bowl, use the back of a spoon or a pastry tart shaper to crush. If in a resealable bag, use a rolling pin to finely crush. Sprinkle on top of the frosting.

Place mini Oreo cookies onto the cake, spacing them apart in 4 rows of 3 cookies each.

Place mini chocolate chips into a resealable sandwich bag but do not seal. Microwave for 45 seconds total, in 15 second increments at 50% power, kneading after each 15 seconds until smooth. Cut a very small tip in the corner of the bag with scissors.

Apply a small amount of chocolate on the back of the eye and attach to the spiders. Repeat until all spiders have eyes. Use the remaining chocolate to create legs on the spider cookies. Let set until chocolate is hard.