Clean and slice the mushrooms and place them in a pan with a knob of butter. Melt the butter over a low heat and add some extra virgin olive oil.
When the fat is hot, add the mushrooms and a whole, peeled garlic clove.
Add salt and pepper to taste and cook for 10 min. (you can replace fresh mushrooms with dried ones).
Cook the tagliatelle, drain while still firm and set aside a glass of the cooking water.
Pour the tagliatelle into the pan with the mushrooms. Raise the flame slightly and, continuing to stir, add the Robiola Osella with Truffle and the cooking water, until you have a soft and smooth cream.
Take off the heat and serve.