¼ cup olive oil 4 cloves garlic, finely chopped 1 small onion, finely chopped 1 tsp. crushed red chile flakes 1 pound sweet Italian sausage, casing removed 1 bunch kale, stemmed and roughly chopped 2½ cups half and half ⅓ cup grated Parmesan Juice and zest of 1 lemon Freshly grated nutmeg, to taste Kosher salt and freshly ground black pepper, to taste 1 pound dried penne pasta 3 tbsp. finely chopped parsley, for garnish
1. Heat oil in a 6-qt saucepan over medium-high heat. Add garlic, onion and red chile flakes; cook, stirring occasionally, until golden brown, about 10 minutes. Add sausage, and cook, using a wooden spoon to break it up into small pieces until browned, 16 to 18 minutes. Add kale, season with salt and pepper, and cook until wilted, about 3 minutes. Add half and half and bring to a simmer; cook, stirring occasionally until reduced by a third, 7 to 8 minutes. Stir in Parmesan, juice and zest, nutmeg, and season with salt and pepper; set aside and keep warm.
2. Bring a large pot of salted water to a boil over high heat. Add penne and cook, stirring occasionally until al dente, 8 to 9 minutes. Drain, reserving ¼ cup cooking water; add both pasta and water to reserved sauce and cook about 5 minutes more. Serve garnished with parsley.