ISO: help with chiffon cake

Hi there. I had a very interesting situation with a heart shaped chiffon layer cake that I was making for an informal wedding reception.

I had to grease the heart pans, layer with wax paper, and grease the wax paper. I forgot to grease the wax paper. I baked the cakes, and they looked lovely in the oven. The recipe required me to let the cakes cool for 10 minutes before I took them out of the pan. When I came back to take them out, they had totally sunk. I took them out of the pans and tried to put them on a wire rack, but that effort failed. I thought it could be because I had forgotten to grease the paper or maybe that I had not beaten egg whites well enough (my recipe asked for soft peaks, but in checking "The Joy of Cooking", chiffon cake need stiff peaks) I made the cakes a second time. I made sure I had stiffer peaks in my egg whites, and I greased the waxed paper. This time it sunk again, except that the edges broke from the rest of the cake because it was stuck to the paper. This did become a 4 layer compact cake, and it was very good despite all my troubles. So I was wondering if there were any secrets to this chiffon cake or in general, and I would really appreciate your input. Thanks!