Wash and dry the spinaches, melt the butter with the finely minced shallot. Cut the spinachs very finely in julienne and keep them apart.
Cook the Plin in abundant boiling salted water for 5 minutes, drain them in the butter, stir carefully and add the spinaches (that will cook with the heat of the pan). Lay some balsamic vinegar drops on the bottom of the plates. Afterwards, put the Plin in the plates and add the castelmagno dop cheese flakes on them.
Serve hot.