Heat the broth in a medium saucepan over moderately low heat and keep at a simmer.
In a large saucepan, heat the oil over moderate heat. Add the onion and saute about 8 minutes, or until soft. Add the pumpkin and saute another 5 minutes.
Stir in the sage. Add rice and saute, stirring constantly, for about a minute. Slowly add the broth, about 1/4 cup at a time, stirring frequently. Don't add more broth until all the liquid has been absorbed.
After the 2 cups of broth have been absorbed, the rice should be tender; add more broth if needed. Slowly stir in the cheese and add salt and pepper to taste.
Serve hot.