Preheat the oven to 375 degrees F. Toss the pumpkin with olive oil and salt and place in a single layer on a sheet tray. Bake in the oven until soft, about 20 minutes. Remove from the oven and reserve.
Bring a large pot of well-salted water to a boil. Set up a bowl of well-salted ice water. Drop the broccoli rabe into the pot of boiling water, swirl it around, remove it from the water and immediately plunge into the salty ice water. Reserve the boiling water. Remove the broccoli rabe from the ice water, squeeze out the excess water and reserve.
Coat a large saute pan with olive oil and add the pancetta and red pepper flakes. Bring the pan to medium heat and cook the pancetta until brown and crispy. Add the roasted pumpkin and about 3/4 cup of the broccoli rabe cooking water. Simmer until the water reduces by half, about 2 minutes.
Meanwhile, add the orecchiette to the reserved boiling broccoli rabe water and cook until al dente, about 1 minute less than the cooking time says on the box. Remove the pasta from the water and add to the pan with the pancetta and pumpkin. Add the broccoli rabe and about 1/2 cup of the pasta cooking water. Cook until the water has evaporated and the sauce clings to the pasta, about 1 minute. Drizzle with olive oil and sprinkle with the grated parmigiana. Toss vigorously.
Divide the pasta among dishes, sprinkle with a little more grated parm and top with the roasted green pumpkin seeds.