Dissolve gelatin in boiling water; add cold water and set aside.
Bake cake according to package directions in 9x13x2 pan (may use jelly roll pan). Cool cake 20-25 minutes. Poke deep holes through top of cake, while still in pan, 1" apart. Spoon jello into holes. Refrigerate.
In chilled bowl, blend and whip, pudding, milk, dream whip and vanilla. Beat till stiff. Ice cake. Cake must be kept refrigerated. Cake may be frozen.