Pliny wrote of eating acorns in his Natural History

“It is a well-known fact that acorns at this very day constitute the wealth of many nations, and that, too, even amid these times of peace. Sometimes, also, when there is a scarcity of corn they are dried and ground, the meal being employed for making a kind of bread. Even to this very day, in the provinces of Spain, we find the acorn introduced at table in the second course: it is thought to be sweeter when roasted in the ashes. By the law of the Twelve Tables, there is a provision made that it shall be lawful for a man to gather his acorns when they have fallen upon the land of another.” (Natural History, Book 16, Chapter 6)

• rinse, cook in boiling water, using two pots.
• roast in single layers on oven tray at 180ºC for an hour or so

“Bring two large stockpots to a boil. Pour the acorns into one pot and let it boil until the water turns dark, usually about 15 minutes. Carefully transfer the acorns to the second pot of boiling water and boil the nuts for about 15 minutes. Refill the first stockpot and bring it to a boil. Keep transferring the acorns from one pot of boiling water to the other until the water stays clear. Drain the acorns in the colander and let cool for about 10 minutes.

Do not rinse your acorns with cold water during the leaching process or you'll bind the tannins to the acorn and they will turn out bitter.”

via https://www.themadfermentationist.com/2018/12/fermented-acorn-sour-brown.html

I inspected each acorn to remove any that were cracked, or otherwise marred. I briefly rinsed them, and then arranged in a single layer on a shallow baking dish in the basement to allow them to dry.

A week later, after discarding those where a larva bored out, I moved the acorns to five lightly sealed pint mason jars. I didn't add water, microbes, or anything else.

Over the next nine months in my 65F basement the acorns slowly fermented on their own. First producing carbon dioxide and the pleasant aroma of ethanol. Then slowly a more complex aromatics of apricot, chocolate, and bourbon. Exactly which microbes are responsible is a mystery to me.

• rinse
• dry
• place in lightly sealed jars
• wait

e.g. https://practicalselfreliance.com/acorn-recipes/

• Torta di ghiande
• Sardinian Acorn Bread (Su Pan’ispeli)
• Acorns are having a renaissance
• Acorn flour and honey, mild, musty, sweetish and densely spongy
• https://edgewood-nursery.com/blog/2020/8/21/the-way-i-collect-and-process-acorns

Ingredientes:

• un puñado de bellotas comestibles (no todas las especies lo son)
• la cáscara de una naranja
• una rama de canela
• dos o tres cucharadas de miel
• canela molida

Preparación:

Se hace una hendidura a cada una de las bellotas en la punta para que puedan coger el aroma, se ponen en un recipiente con agua, con la cáscara de la naranja, la rama de canela, la miel y canela en polvo y se dejan hervir durante 25 minutos aproximadamente. Se escurren del agua y se sirven con la canela como aperitivo o dulce.

Ingredientes:

• bellotas dulces, 1 kilo
• azúcar, 1 kilo - manteca de cerdo, 1/2 kilo
• huevos, 2 unidad
• chocolate, 4 onzas
• canela, al gusto
• ralladura de limón
• harina, al gusto

Elaboración:

Quitar la cáscara a las bellotas, escaldarlas y quitarle la piel. Dejar que se sequen bien y molerlas muy finamente. Mezclar las bellotas molidas con el resto de los ingredientes y amasar bien. Engrasar un molde y aplastar bien la masa, adornar con almendras crudas enteras clavadas en la masa y meter al horno hasta que esté bien dorada.