In a large skillet, bring enough water to cover the asparagus to a boil, add 1 teaspoon salt and the asparagus, and boil until tender, about 5 minutes. Remove the asparagus from the cooking water. Simmer the water to evaporate it to ½ cup and add it to the broth. Cut off the asparagus tips and set aside. In a food processor, purée the asparagus stalks until creamy.

Keep the broth warm in a saucepan over low heat. In a skillet, melt 2 tablespoons of the butter with the olive oil over low heat. Increase the heat to medium, add the leek and shallots and sauté until softened, about 5 minutes. Add the rice and sauté for several more minutes until the grains are opaque and click softly as you stir. Stir in the wine and cook until almost all the liquid has been absorbed. Stir in a ladleful of hot broth. Reduce the heat to low. When that liquid is nearly all absorbed into the rice, add another ladleful of hot broth. Continue in this manner, adding broth a ladleful at a time and permitting it to become absorbed before adding another ladleful of broth. Stir occasionally to prevent the rice from sticking to the pan. After the last ladleful of broth is added, stir in the asparagus purée. The rice should be tender but still slightly chewy, and the overall texture creamy and loose. Taste for salt. Remove from the heat, stir in the asparagus tips, the remaining 2 tablespoons butter, and the ½ cup parmigiano-reggiano.

Immediately divide the risotto among individual wide bowls. Distribute the provola over each serving. Serve piping hot, adding pepper as desired, and pass additional parmigiano-reggiano at the table.