Toss the beechnuts in a sieve over an open fire until they are roasted, then remove the skins.
Melt butter and sugar in a frying pan and caramelize until brown, about 10 minutes. Check for firmness by tasting a tiny bit of caramel set on a small spoon.
Add the peeled beechnuts to the caramel form and caramelize for another 1-2 min. Transfer the beechnuts to an oiled baking sheet or one that may be lined with parchment paper.
While the caramel is cooling, cut it into small, square pieces.