Spaghetti With Mushroom Cream Sauce

Well I was so happy to have a mushroom extravaganza, I may be overlooking some flaws, but I loved it.  I would have liked it better if I had spent $$$ and had all shiitake and other fancier mushrooms but it just wasn't in the budget.  Not bad with the button mushrooms but, all of the more expensive variety would have been stellar.  It was very rich and creamy.  I cut the mushrooms smaller than indicated so my son wouldn't have big pieces of mushroom to make him gag.  He ate it all but he wasn't very happy about it.

Spaghetti With Mushroom Cream Sauce
12 oz dried spaghetti
Kosher salt
1    Tbs. extra-virgin olive oil
1    Tbs. unsalted butter
1    large shallot,finely chopped
1 lb mixed mushrooms,cleaned, trimmed, and sliced 1/4 inch th
Freshly ground black pepper
2    Tbs. tawny port
1/2 c  heavy cream
1/2 c  sour cream
3    Tbs. chopped fresh parsley or 2 Tbs. chopped fresh tarragon
Grated Parmigiano-Reggiano for serving
Over high heat, cook the spaghetti in a large pot of boiling salted
water according to the package directions until al dente.
Meanwhile, heat the oil and butter in a 12-inch skillet over medium-
high heat. Add the shallot and cook, stirring, until it just begins to
color, 1 to 2 minutes. Add the mushrooms, 3/4 tsp. salt, and a few
grinds of pepper and stir constantly until the mushrooms begin to
release their liquid, about 3 minutes. Lower the heat to medium and
cook, stirring occasionally, until soft and lightly browned, about 5
minutes more.
Add the port and stir to deglaze the pan. Add the cream and sour cream,
bring to a simmer, and reduce the heat to medium-low. Cook, stirring
frequently, until the liquid reduces to a saucy consistency, about 2
minutes.
When the spaghetti is al dente, reserve 1/2 cup of the cooking water
and drain the spaghetti. Add the spaghetti and the reserved water to
the sauce. Toss over low heat, sprinkle with the parsley or tarragon,
and toss again to combine. If the sauce seems thin, continue to toss
until it has thickened a bit. Season to taste with more salt and pepper.
Serve,  sprinkling with the parmigiano at the table.