If your cheesecake ingredients are too cold they will require longer mixing and longer mixing adds too much air into the filling which can cause air bubbles on the surface of your cheesecake and will cause your cheesecakes to sink in the middle. These cheesecakes will sink slightly because the edges of the cheesecakes will bake faster than the middle. I don't mind that as it makes a nice surface to add toppings that won't slide off. But overmixed batter will cause them to sink a lot which won't look attractive. Using a hot water bath can keep the edges of the cheesecakes from baking more quickly than the center. I baked my Conversation Heart Cheesecakes in silicone molds in a water bath. If you do choose to use a water bath, be sure to use silicone cupcake pans. Do not overmix the cheesecake filling and be sure to use LOW speed if using a mixer.