Pasta with onions and beans
Description
In a large skillet, heat 1 tablespoon of butter over medium heat. Add leek, 3/4 teaspoon salt, and 1/4 teaspoon pepper. Cook, stirring frequently, until softened, about 10 minutes. Add beans, broth, and sage. Using a potato masher, mash one-third of the beans. Bring to a boil, then reduce heat. Cook until the sauce thickens, about 10 minutes. Let cool. The sauce can be refrigerated for up to 2 days before using. Meanwhile, in a large pot of boiling salted water, cook pasta for 2 minutes less than the package instructions. Drain and rinse under cold water, then transfer to a bowl. Toss with the remaining tablespoon of butter. Cover and set aside. In a large saucepan over medium heat, bring the sauce and lemon juice to a boil. Stir in cream and Parmesan. Add the pasta and cook, stirring, until heated through, about 2 minutes. Sprinkle with parsley and serve with cheese, if desired.