Preheat oven to 350 degrees. Lightly grease and flour a 13-x-9-x-2-inch pan; set aside.
In a large bowl, combine dry cake mix, water, lemon extract, gelatin mix, oil and eggs; beat with an electric mixer for at least 3 minutes. Spread batter in prepared pan.
Bake for approximately 35 minutes.
When cake is done, prick entire cake with fork. Mix confectioner's sugar, lemon juice and zest. Pour this mixture on top of warm cake. Serve plain or with whipped cream.