Bake cake in a 9x13" pan according to directions on the box. Let cool for at least 30 minutes.
Dissolve jello in boiling water. Add cold water; set aside.
Using the handle of a plastic or wooden spoon, poke holes all over the cake about 3/4 of the way down into the cake.
Carefully pour the jello mixture over the top of the cake, trying to get as much into the holes as you can. Cover and chill for at least 3 hours, or overnight.
For frosting: Beat cream in a cold bowl till soft peaks form; beat in powdered sugar and vanilla. Set aside.
Beat together pudding mix and the one cup of milk with a hand mixer till smooth, about a minute. Fold in the whipped cream mixture.
Spread frosting over cake. Garnish with fresh sliced strawberries. Serve immediately or cover and store in the refrigerator.