Cook the linguine; while it is cooking, make the mushroom topping.
Heat butter in a large skillet. Add the mushrooms and saute for a moment, Add a cover and a tad of water and simmer for 5 minutes or until tender. Remove the cover and evaporate the liquid. Add the garlic and saute just until aromatic. Remove mushrooms from the heat and season well to taste with salt and pepper.
When the pasta is done, return it to the cooking pot and toss with mushrooms, hazelnut oil and parsley; keep on tossing until well combined and transfer to 2 heated pasta bowls. Garnish with hazelnuts and dinner is done. Accompany with steamed vegetable salad.