Prepare the cake mix according to the package instructions.
Line mini cupcake pan with small paper-liners. Fill liner with about 1 tablespoon of batter.
Bake in a preheated 350℉ for about 10-12 minutes or until no longer gooey in the middle. Watch them closely, so they do not burn. Transfer to a wire rack, and cool completely.
Spread the tops of the cupcakes with frosting. Then, coat the tops with chocolate sprinkles.
Cut the marshmallows in half crosswise. Using the reserved frosting in a bag, cut a small hole in the corner of the bag. Attach teh two halved marshmallow pieces to each cupcake as eyes. Dot hte center of each marshmallow piece with frosting, and attach the M&M's. Make sure the M&M's are facing in, so they do not have Ms on their eyes.
Cut each licorice lace into one inch pieces. Press four holes into two sides of each cupcake using the toothpick. Insert a licorice piece into each hole for each spider's legs. I used 8 pieces for 8 legs.
Notes
It is vital that you let the cupcakes completely cool before assembling. If you put on thick frosting, it will be faster to stick your licorice legs in.