Step 1

Heat olive oil in a large skillet over medium heat. Cook and stir white and shiitake mushrooms in the hot oil with a pinch of salt until until the juice from the mushrooms evaporates and the mushrooms are browned, about 10 minutes.

Step 2

Stir garlic into mushrooms and cook for 1 minute; pour in sherry and cook until wine is nearly evaporated. Mix chicken stock into mushroom mixture; season with salt and black pepper. Bring to a simmer, reduce heat, and cook until slightly thickened, about 5 minutes.

Step 3

Pour cream into mushroom mixture, stir to combine, and simmer for 5 minutes. Mixture will foam and thicken slightly.

Step 4

Fill a large pot with lightly salted water and bring to a rolling boil. Stir in the fettuccine, bring back to a boil, and cook pasta over medium heat until cooked through but still firm to the bite, about 8 minutes. Drain but do not rinse pasta; transfer to a large serving bowl and keep warm.

Step 5

Stir thyme, chives, and tarragon into mushroom sauce and turn off heat; mix 1/2 cup Parmigiano-Reggiano cheese into sauce until cheese has melted.

Step 6

Pour all the mushroom sauce and half the mushrooms over pasta, reserving about half the mushrooms in the skillet. Toss pasta in sauce until coated; top with remaining mushrooms and remaining 1 tablespoon Parmigiano-Reggiano cheese for garnish.