Oven drying. First of all, the
chestnuts must be dried in the oven at a temperature of 150° for about 20 minutes. It is necessary to check that they are thoroughly dry. They can also be cooked like roasted chestnuts in a perforated pot, but care must be taken not to let them become too black or burnt.
Powdering. After drying, wait for the
chestnuts to cool down and proceed to powdering, which can be done either with the ancient technique of grating or with a blender. The important thing is that they are well dried; otherwise, if they are damp, the granules will remain too large. If they turn out to be damp even in the end, put them back in the oven for a few more minutes at the same temperature. But be careful not to let them brown too much.
At this point, it's ready.