Ingredients

Kosher salt and freshly ground black pepper 

12 ounces long pasta, such as linguine or spaghetti 

1/4 cup extra-virgin olive oil 

1 large or 2 medium shallots, thinly sliced (1 cup) 

1 pound button or cremini mushrooms, sliced (6 cups) 

1 tablespoon prepared horseradish 

1/2 cup creme fraiche, plus more for serving 

2 tablespoons chopped fresh dill, plus sprigs for serving 

Preparation

Bring a large pot of salted water to a boil. Add pasta and cook until slightly less than al dente, about 2 minutes less than package directions. Reserve 1 cup pasta water, then drain.

Meanwhile, heat oil in a large straight-sided skillet over medium-high. Add shallots; cook, stirring, until translucent, about 2 minutes. Add mushrooms, season with salt and pepper, and cook until tender and browning in spots, 7 to 9 minutes. Stir in horseradish, pasta, and 1/2 cup pasta water; cook, stirring and shaking pan until pasta is cooked and sauce begins to coat pasta, 1 to 2 minutes. Remove from heat and stir in creme fraiche and chopped dill; continue stirring and shaking pan, adding more pasta water as needed to create a creamy sauce. Serve, garnished with more creme fraiche, dill sprigs, and pepper.