How to Make It
Bring the stock to a boil in a medium saucepan, cover and keep hot. Melt the butter in a large saucepan. Add the onion, celery rib and chile, season with salt and pepper and cook over low heat, stirring, until softened, about 7 minutes. Add the celery leaves and garlic and cook for 1 minute. Add the rice and cook, stirring until glossy, about 1 minute
Add the vermouth to the rice and simmer over moderate heat until almost absorbed, about 3 minutes. Add the hot stock, 1 cup at a time, and cook, stirring constantly between additions, until most of the stock has been absorbed before adding more. The rice is done when it's tender and most of the liquid is absorbed, about 20 minutes total. Stir in the 1/2 cup of Parmesan cheese, the mascarpone, the lemon zests and juices and the basil. Season with salt and pepper. Spoon the risotto into bowls and serve, passing additional Parmesan at the table.