Preheat the oven to 375°F.
In a large bowl, toss the butternut squash with just enough olive oil to lightly coat and sprinkle it with salt. Put the squash on a baking sheet and roast for about 20 minutes or until soft; reserve.
Bring a large pot of well-salted water to a boil. Add broccoli rabe, give it a swish and immediately remove it from the water; save the water to cook the pasta. When the rabe is cool enough to handle, coarsely chop it and set aside.
Coat a large wide saucepan generously with olive oil. Toss in the garlic and red pepper, and bring to medium heat. When the garlic is golden brown and very aromatic, 2-3 minutes, remove it from the pan and ditch it—it has fulfilled its garlic destiny. Add the roasted squash and the stock to the pan. When the stock has reduced by about half, 5-6 minutes, add the broccoli rabe.
In the meantime, bring the broccoli rabe water back to a boil, add the pasta and cook for 4-5 minutes or until tender but toothsome. Drain the pasta and add it, along with 1/2 cup reserved pasta cooking water, to the squash and rabe. When the pasta water has evaporated, remove the pan from the heat, add about two-thirds of the Parmigiano and a big drizzle of the big fat finishing oil. Toss or stir vigorously to combine. Divide among serving bowls and top with more Parm and pepitas.