Prepare pudding with milk; add softened gelatine and stir until dissolved. Stir
in vanilla extract.
Line sides of springform pan with 4 pineapple slices alternating with 4 jellyroll
slices. Fold Dream Whip or Cool Whip into pudding. Spoon one-third of the pudding
into pan. Arrange a layer of jellyroll slices over pudding.
Repeat layers, ending
with pudding. Top with pineapple slices.