These little airy puffs may collapse easily. However, some simple tips will help you prevent this from happening. First, never open the oven door as the puffs bake. The rush of air will likely cause them to collapse. Also, you want to leave plenty of space between each one. If you stick to this simple advice and your puffs still fall in when you remove them from the oven, you may need to adjust the temperature and cooking time with the next batch. Lower the heat from 400 to 375 degrees and bake for a few extra minutes until the puffs are a light golden brown. This should solve the deflating problem.