Preheat the oven to 400 degrees F. Halve the pumpkin and scoop out the seeds. Cut the pumpkin into 8 equal wedges and arrange on two baking sheets lined with foil. Sprinkle the wedges with salt and pepper and drizzle lightly with olive oil. Bake until the pumpkin is caramelized and tender when pierced with a sharp knife, about 1 hour.
Remove from the oven and let cool until you can handle the pumpkin without burning yourself. In the meantime, crisp the proscuitto in a medium saucepan over medium heat, about 10 minutes. Remove and drain on paper towels, discarding the fat.
Turn the oven up to 500 degrees F. Bring a large pot of salted water to a boil. Cook the pasta for exactly 5 minutes, then drain and run cool water over it for about 10 seconds. Set aside in the colander.
Scoop enough of the cooked pumpkin from the rind to make 2 cups. Combine this with the cream in a blender and puree just until smooth Scoop out some more of the pumpkin and chop roughly to make about a cup and a half. Combine the pumpkin and cream puree with the cheeses, salt, thyme and pancetta in a large bowl and stir gently to combine. Add the pasta and the chopped pumpkin and fold together just until combined. Spread the pasta evenly in a casserole or baking dish. Bake uncovered until the top is browned and the bottom layer of pasta is just tender, 7 to 10 minutes.