One of the most defining characteristics of an excellent éclair is the contrast between the crispy outer shell and the creamy filling. Make sure to bake your elcair shell until it is golden brown and crispy on the outside - leaving the inside soft and slightly moist. Overbaking the eclair shell can result in a dry, hard, crunchy shell. Underbaking the pastry will create a soggy eclair. Additionally, try to serve your eclairs the same day they are filled. For one, allowing a filled eclair to remain uneaten for too long is a sin, but it also allows time for the moisture from the filling to seep into the shell. When this happens you are left will a soft, soggy eclair.