Ingredients:

Cake:
1 box lemon cake mix
1 small box lemon jello
3/4 cup vegetable oil
3/4 cup water
1 tsp. lemon extract
4 eggs

Icing:
3 Tbsp. butter
3 Tbsp. lemon juice
1 cup sifted powdered sugar

Preparation:

Mix all ingredients with a mixer for 4 minutes. 
Pour into a 9 X 13 greased and floured pan. 
Bake at 350 degrees F for about 40 minutes or until tester comes out clean.
Remove from oven and pierce cake with a fork. 

Heat icing ingredients on stove until melted. 
Pour over cake while cake is still hot.