In a large pot of salted boiling water, cook the pasta until slightly tender. Keep about 125 ml (½ cup) of cooking water aside. Drain the pasta and oil lightly. Set aside.
Meanwhile, in a large skillet, heat the truffle paste in the butter for about 1 minute. Add 60 ml (¼ cup) of the reserved cooking water, the Parmesan, and mascarpone cheese. Stir to combine. Cook gently until the cheese has melted.
Add the pasta and coat thoroughly with the sauce. Add cooking water, as needed. Generously season with salt and pepper. Divide among four plates. Garnish with slices of fresh truffles.
Truffle paste is often made with summer truffles, oil, and flavourings. It is sold in small jars or tubes in specialty grocery stores.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.