Toss cubed butternut squash with olive oil and salt. Roast at 400°F (200°C) for 25 minutes until tender and caramelized.
Cook pasta shells in heavily salted boiling water until al dente. Drain and set aside.
Transfer the roasted squash to a blender along with the heavy cream, vegetable broth, and minced garlic. Blend until completely smooth.
Pour the squash mixture into a large pot over medium heat. Stir in the butter, grated cheddar, and parmesan cheese until melted and velvety.
Fold the cooked pasta into the cheese sauce. Top with fresh sage leaves crisped in butter and serve immediately!