Heat olive oil in a large, heavy pot over medium-high heat. Sauté shallot until just soft. Add rice and sauté, stirring frequently, 2 to 3 minutes.
Pour a ladleful of hot chicken stock into the mixture; stir constantly until the stock evaporates. Pour another ladleful in and stir until stock is absorbed. Keep doing this for 14 minutes longer. Add just enough hot chicken stock each time to keep the rice from sticking. Slowly, the rice will become creamy.
After that 14 minutes, when the rice is getting softer but is still not entirely cooked in the center, add greens. Continue adding stock for another 2 minutes, then add prosciutto. Stir another minute and continue adding chicken stock until the rice has just the right texture: Each grain should retain its shape, but the overall risotto should have a velvety creaminess. Add butter and salt.
Season to taste with pepper, and serve with lots of grated cheese.