Preparation Bring chicken broth and Sherry to boil in medium saucepan over high heat. Reduce heat to low; cover and keep warm. Meanwhile, heat oil and 2 tablespoons butter in heavy large saucepan over medium heat. Add onion and squash; cook until onion is translucent, stirring often, about 10 minutes. Add rice; stir until rice is translucent at edges but still opaque in center, about 3 minutes. Add 1 cup warm broth; simmer until almost absorbed, stirring often, about 4 minutes. Add more broth, 1 cup at a time, allowing each addition to be absorbed before adding next until rice is just tender, stirring frequently, about 25 minutes total. Stir in chestnuts, thyme, and marjoram. Remove from heat; stir in remaining 1 tablespoon butter, cheese, and parsley. Season risotto with salt and pepper and serve.
Preparation Bring chicken broth and Sherry to boil in medium saucepan over high heat. Reduce heat to low; cover and keep warm. Meanwhile, heat oil and 2 tablespoons butter in heavy large saucepan over medium heat. Add onion and squash; cook until onion is translucent, stirring often, about 10 minutes. Add rice; stir until rice is translucent at edges but still opaque in center, about 3 minutes. Add 1 cup warm broth; simmer until almost absorbed, stirring often, about 4 minutes. Add more broth, 1 cup at a time, allowing each addition to be absorbed before adding next until rice is just tender, stirring frequently, about 25 minutes total. Stir in chestnuts, thyme, and marjoram. Remove from heat; stir in remaining 1 tablespoon butter, cheese, and parsley. Season risotto with salt and pepper and serve.