How to Make It
In a very large skillet, heat 2 tablespoons of the olive oil. Add the white and shiitake mushrooms, season with salt and pepper, cover and cook over moderately high heat for 5 minutes, stirring once. Uncover and cook over high heat, stirring once, until the mushrooms are browned all over, about 3 minutes. Add the sliced garlic, the shallot and rosemary and cook, stirring, until fragrant, about 2 minutes. Add the Marsala and cook until evaporated, about 30 seconds. Add the vinegar and cook, stirring, for 30 seconds. Stir in the minced garlic, olives and the remaining 3 tablespoons of olive oil and season with salt and pepper. Cover and keep warm.
In a large pot of boiling salted water, cook the spaghetti until al dente; drain. Return the spaghetti to the pot. Stir in the butter and mushrooms and season with salt and pepper. Stir in 1/3 cup of the Parmesan. Transfer the spaghetti to bowls, sprinkle with the chives and serve, passing more Parmesan at the table.
Variation The mushrooms can be folded into an omelet, or served with pan-fried chicken breasts or cheese grits.