get a pack of betty crocker ready mix for oatmeal cookies, 1 egg and 100g butter or shortenning.
mix all and split the dough in 2 bowls (or more according to imagination)
for fun, get food coloring and mix in the bowl (gree "shrek" cookies are a must with DS)
Also buy some sprinkly bits, or smarties and decorate.
UUse raisins and other dried fruit to make eyes, nose etc....
have fun