For an eggless version, add 1/8 cup each of oil and buttermilk, ie. the quantities of both used will be 3/4 cup each.
If you can't find buttermilk, you can use laban if you are in the Gulf, OR whisk yogurt and water 2:1 to make a liquid OR add 1/2 tsp vinegar in the said amount of milk and allow it to stand for 5 minutes, to make faux pas buttermilk.
Try to use the same pan for baking and assembling. I baked the cake in a different pan so it was slightly smaller than the springfoam, but nevertheless, it stayed well.