Begin by bringing a large pot of salted water to a rolling boil. Add the tagliatelle and cook according to package instructions until al dente, usually around 8-10 minutes. Reserve about 1 cup of the starchy pasta water to help thin the sauce later. Drain the tagliatelle, but do not rinse; keep it warm while you prepare the sauce.

In a large skillet, heat 2 tablespoons of olive oil or butter over medium heat. Add minced garlic and shallots, stirring continuously for about 2-3 minutes until they become translucent and fragrant.

Incorporate 8 ounces of sliced mushrooms into the skillet, stirring well to coat them with the sautéed aromatics. Continue to cook for about 5-7 minutes, allowing the mushrooms to brown and soften.

Pour in ½ cup of white wine, scraping the bottom of the skillet to release any flavorful browned bits. Let the mixture simmer for about 3-4 minutes until the wine has reduced by half.

Reduce the heat to low and stir in 1 cup of heavy cream or half-and-half. Gradually stir in the reserved pasta water, ¼ cup at a time, until you reach your desired consistency for the sauce.

Add ½ cup of grated aged Parmesan cheese to the sauce, stirring until it melts and combines smoothly.

Gently add the cooked tagliatelle directly into the sauce, tossing it carefully until well-coated. Allow the pasta to absorb some of the sauce for about 1-2 minutes over low heat.

Plate the creamy mushroom Parmesan tagliatelle on warm dishes. Garnish generously with additional grated Parmesan cheese and freshly cracked black pepper.