Peppery arugula is the ideal foil for creamy Arborio or Carnaroli rice in this side dish.
Bring chicken stock to a simmer in a large stockpot over medium heat; cover, and keep at a steady simmer until ready to use. At the same time, heat oil in a large heavy-bottom saucepan over medium heat. Add shallots to oil; cook, stirring occasionally, until shallots are softened and translucent, about 10 minutes. Add rice, and cook, stirring constantly, until rice is thoroughly coated and makes a clicking noise, 3 to 4 minutes. Add wine; cook, stirring constantly, until wine is completely absorbed.
Using a ladle, add about 1 1/2 cups hot stock to the rice; cook, stirring constantly with a wooden spoon, until most of liquid has been absorbed and mixture is just thick enough to leave a clear trail behind the spoon. Add another 3/4 cup hot stock to rice; cook, stirring constantly, until most of liquid is absorbed.
Continue adding stock 3/4 cup at a time, stirring constantly after each addition, until the rice is mostly translucent but still opaque in the center, and the liquid is the consistency of heavy cream, 20 to 25 minutes. The rice should be al dente but no longer crunchy. Watch carefully, and gradually reduce the amount of added liquid to make sure the mixture does not overcook; it will continue to thicken after it is removed from heat.
Remove from heat. Stir in butter, cheese, and arugula puree; season with salt and pepper. To serve, mound risotto in the center of shallow serving bowls, and sprinkle with additional cheese. Garnish with arugula flowers, if desired.
Since this recipe makes a large quantity of risotto, be sure to use a wide shallow saucepan or skillet to let the rice cook evenly.