The time that French crispy cakes stay crisp is directly related to the weather. Because crispy cakes are the best time to be crisp when they are completely cooled out of the oven. If you pack it in food bags at this time, you can keep the crisp effect for a long time. Otherwise, over time, the cake will absorb trace moisture in the air, so it is inevitable that the more humid the air is, the shorter the crispness will be, and it will not be brittle after a long time.

Brittleness is relative, not absolute. If the crispy cake is still crisp if it is kept indoors for a long time without sealing, it is definitely added with other additives, which are harmful to human body and are forbidden to be used in food.