This easy pasta dish takes less than 30 minutes and less than 10 ingredients to make. The gorgonzola packs a creamy punch of flavor that is well balanced by the Parmesan and buttery spinach. The finely chopped toasty walnuts add a nice crunchy texture to each bite.
Bring a large pot of salted water to a boil. Add the pasta and cook as the label directs for al dente. Reserve 1 cup cooking water, then drain.
Meanwhile, toast the walnuts in a large skillet over medium heat, shaking the pan occasionally, until golden brown, 3 to 5 minutes. Remove the walnuts to a cutting board (reserve the skillet) and let cool slightly, then very finely chop.
In the last 2 minutes of cooking the pasta, add the butter to the skillet and melt over medium heat. Add the spinach, cover and cook until wilted, 1 to 2 minutes. Add the cooked pasta, gorgonzola, Parmesan, 1/2 teaspoon each salt and pepper and 1/2 cup of the reserved cooking water to the skillet. Toss until the cheese is melted and the pasta is evenly coated in the sauce. Add more pasta water as needed; season with salt.
Divide the pasta among shallow bowls and top with the walnuts. Drizzle any remaining sauce in the skillet on top.