Cook pasta in a large pot of boiling salted water, stirring occasionally, until al dente. Drain pasta, reserving 1 cup pasta cooking liquid.
Meanwhile, bring cream to a simmer in a large skillet over medium-high heat and cook, stirring occasionally, until reduced by half, about 4 minutes. Whisk in pumpkin purée; season with 1/2 tsp. salt and 1/2 tsp. pepper.
Add pasta and 1 cup reserved pasta cooking liquid to skillet and cook, tossing to coat, until sauce has reduced, 3–4 minutes. Season with remaining 1/2 tsp. salt and 1/4 tsp pepper. Top with freshly ground pepper before serving.
