Mushroom lovers, this one's for you.
Preheat the oven to 300°.
Bring a large pot of water to a boilfor the pasta.
Chop the nuts and place on a small baking sheet. Toast in the oven until golden and fragrant, 8 to 10 minutes.
Meanwhile, in a large (12- to 14-inch) skillet, melt the butter over medium heat; cook, stirring often, until brown and fragrant, 3 to 4 minutes. Add the mushrooms; cook until browned, stirring occasionally, 15 to 20 minutes. Season with kosher salt, black pepper, and white pepper. Add the thyme, garlic, and lemon juice; toss until coated, about 1 minute. Add the kale; toss until wilted, 4 to 5 minutes. Stir in the nutmeg, then the cream; cook, stirring often, until heated through, about 1 minute.
After the mushrooms have been browning for 10 to 12 minutes, salt the boiling water, add the pasta, and cook until 1 minute shy of al dente. Reserve about 1 cup of the pasta cooking water just before draining.
Drain the pasta and toss with the mushrooms, 1 cup cheese, and the pasta cooking water. Season; top with the nuts. Pass more cheese at the table.