This is one of my *favorite* cakes. I first heard about it on Pinch My Salt (which is where the pic is taken from) http://pinchmysalt.com/2007/09/14/quick-and-easy-lemon-cake/
The only change I made from her recipe (which has some cute pics to go along w/the instructions) is to use a lemon box cake mix instead of a yellow one. I was never a lemon cake fan before trying this cake but now I'm truly addicted.
NOTE: You will have to make adjustments if you live in a high altitude.
1 package lemon cake mix
1 small package lemon jello
3/4 C. water
4 eggs, well beaten
3/4 C. oil
Juice and zest of 2 lemons
2 C. powdered sugar
1. Preheat oven to 350. Butter and flour a 18 x 13-inch jelly roll pan (I use 2 8x8" pans)
2. Pour cake mix and lemon jello powder into a large bowl; mix. Stir in the water then add eggs and oil. Mix using a wooden spoon. Lumps ok
3. Pour batter into a greased and floured pan; smooth batter with a spatula so that it is even. Bake 25 minutes at 350 degrees, checking after the first 20 minutes.
4. While cake is baking, mix together powdered sugar, lemon juice and zest.
5. While cake is still warm, pierce with fork all over then spread glaze evenly over the top. Allow to cool, then cut into squares and serve.