Bring broth to simmer in medium saucepan over medium heat. Reduce heat to low and keep warm. Melt butter in large saucepan over medium heat. Add chopped green onions and cook until soft, stirring often, about 6 minutes. Stir in rice. Add wine; cook until almost all liquid is absorbed, stirring frequently, about 2 minutes. Add 4 cups broth, 1 cup at a time, cooking until almost all broth is absorbed before adding more, stirring frequently, until rice is tender but still firm, about 20 minutes. Stir in sliced green onions, Parmesan, mascarpone, and orange peel. Add more broth by 1/4 cupfuls as needed if dry. Season with salt and pepper.