1 3-ounce box lime gelatin
1 cup boiling water
1/2 cup cold water
1 22-ounce can Key Lime Creme pie filling and topping
1 8-ounce container Cool Whip
fresh lime zest for decorating
Preheat oven to 350 degrees F. and prepare a 9 X 13-inch baking dish by spraying the bottom with cooking spray. Mix cake according to package directions. Bake for 30 minutes or until a toothpick inserted into the middle comes out clean. In a small bowl, mix lime gelatin with one cup of boiling water until completely dissolved. Mix in the 1/2 cup of cold water. Remove the cake from the oven and allow to cool for 5 minutes. With the end of a wooden spoon, poke holes into the cake about 1 1/2 inches apart. Slowly drizzle the gelatin over the entire surface of the cake so that it is covered and drips into the holes. Refrigerate for at least two hours. Spread the Key Lime Creme Pie topping over the cake and then cover completely with Cool Whip. Return to refrigerator to cool for at least one hour before serving. Decorate with fresh lime zest and lime slices, if desired.