If the batter does not fall back into the bowl, you need to add more egg. In which case, whisk a whole egg and add as needed. Sometimes a whole egg is too much, so you need to only add half of the egg. The profiteroles may be baked in advance and kept in the freezer for up to 1 month. They may be toasted in the oven about 30 minutes before serving at 325 degrees F for about 4 minutes to taste fresh again.