Mix both boxes according to directions and combine the batter. I
generally use a large mix bowl and add both boxes together. I add
the other ingredients all at once. If you have only small boxes
of jiffy mix, use a brownie size 8-inch square baking pan. If you
use a box of regular cake mix, use a 9 x 13-inch pan.
Bake at 350 degrees F until done. This takes about 30 minutes. Test for doneness.