Mushroom and Garlic Spaghetti
1 pound dry spaghetti
3 tablespoons unsalted butter, divided
1 tablespoon olive oil
1 pound cremini mushrooms, cleaned and sliced (I prefer White Button)
Freshly ground black pepper
6 cloves garlic
1/2 cup grated Pecorino Romano cheese, plus more for serving
2 tablespoons coarsely chopped fresh flat-leaf parsley leaves
Bring a large pot of salted water to a boil. Add the pasta and cook until al dente, 7 to 9 minutes, or according to package instructions. Reserve 3/4 cup of the cooking water, drain the pasta, and set it aside.
Meanwhile, heat 1 tablespoon of the butter and the oil in a large skillet over medium heat. Add the mushrooms, season with salt and pepper, and sauté until browned and tender, about 5 minutes.
Add the garlic and remaining 2 tablespoons butter and sauté for 1 minute more.
Add the cooked spaghetti, reserved cooking water, and 1/2 cup cheese. Toss and stir until the water has just evaporated and the cheese has melted into the pasta, about 2 minutes.
Add the parsley and toss once more to combine.
Serve in shallow bowls, sprinkling with additional grated cheese over each serving.