Many German cheesecake recipes result in the cake cracking after it is baked. But there are some simple tricks to prevent this. The higher the cheesecake the more prone to cracking it is. A very wet and airy filling can also be a problem. That's why I recommend straining the Greek yogurt so it is more similar to quark and whipping the heavy cream before adding it. Baking the cake at a low temperature and letting it sit in the turned-off oven also helps a lot. Sudden temperature changes can cause the top cake to break. If you still end up with a not-perfect cheesecake, just sprinkle some powdered sugar on top or add some fresh fruit.