Bring a large pot of water to a boil. Once boiling, generously season the water with salt. Add the cavatappi (or pasta of choice) and cook, stirring occasionally to prevent sticking, to al dente. (Al dente cooking time is typically noted on package directions.) Once the pasta reaches al dente, drain the pasta – but do not rinse – and set aside.
Meanwhile, as the pasta boils, transfer the butternut squash soup to a medium saucepan over medium-high heat. Cook, stirring occasionally, until the soup is warmed through and bubbling. Whisk in the Dijon mustard, garlic powder, and ground nutmeg. Season with ½ teaspoon kosher salt and ground black pepper. Reduce heat to low.
Just as the pasta reaches al dente, melt the cheese into the butternut sauce. Working one handful at a time, add the cheese to the warm butternut squash mixture. Stir to combine well. Once melted completely, repeat with another handful of cheese. Continue until all of the cheese is added and melted; the butternut squash cheese sauce will be deliciously thick and creamy. Taste and adjust seasonings as desired and remove from the heat – at this point the pasta should be ready.
Add the al dente pasta to the butternut squash cheese sauce, tossing to combine well. Portion the butternut squash mac and cheese into individual bowls, topping with grated additional grated parmesan cheese or crispy fried sage leaves as desired. Serve immediately. Enjoy!