Peel and dice the potatoes and cook in salted water for 25 minutes, then drain and allow to evaporate, then mash with a potato masher.
Bring the milk to the boil briefly and melt the butter in it, then gradually mash under the potatoes together with the cheese until the puree has the desired consistency.
Finely grate a truffle and stir it into the puree, season with truffle oil and salt. Arrange and slice the other truffle over the puree.