Bake strawberry cake according to directions on box
Let cool
Mix small box of strawberry jello with 1 cup boiling water (do not add the cup of cold water), and mix well until dissolved
Poke cake all over with fork and pour jello mixture on top, evenly
Let cool in refrigerator for at least 1 hour
Spread half of container of frozen strawberries on top of the cake
Mix the other half with the tub of cool whip and spread on top as frosting