Using the Sour Cream Butter Cake recipe: Instead of using 4 large egg yolks (which equals 2 full fluid oz), I substituted 1 whole egg because it measured the same 2 full fluid oz. The batter seemed perfect when I poured it into the springform pan. I began testing early, around 30 minutes but the pan seemed too jiggly. So, I checked every 5 minutes. Probably very close to the 45 minute baking time, I checked with a toothpick and it came out clean—so I removed the cake to cool. It did not rise to the 1 3/4 inch height; and in fact, it fell quite a lot in the middle. But, it was a very delicious cake. I would like to solve this problem for the future. Does the problem of a shorter cake and fallen cake center lie in the fact that I made the egg substitution (even though the liquid measurement was the same)? Or, did I need to bake the cake longer?