Dissolve gelatin in ¾ cup boiling water. Add ½ cup cold water; set aside at room temperature. Mix and bake cake as directed in a 13 x 9 x 2-inch pan. Cool cake 20-25 minutes. Poke deep holes through top of warm cake (still in pan) with meat fork or toothpick; space holes about one inch apart. With a cup, slowly pour gelatin mixture into holes. Refrigerate cake while preparing topping.
**** Topping *****
In a chilled, deep bowl, blend the whipped topping mix, instant pudding, and cold milk until stiff (3-8 min.). Immediately frost cake. If desired, garnish with thin lime or lemon slices.
Cake must be stored in refrigerator and served chilled. Frosted cake may be frozen for storage.