Step 1 Heat the oil in a deep heavy skillet over low heat. Stir in the onion and cook slowly until softened and translucent but not browned, 2 to 3 minutes. Mix in the rice and stir for 3 to 4 minutes until the outer shell of the rice becomes translucent, showing the pearly "eye" at the center.
Step 2 Add the wine and simmer, without stirring, for 2 to 3 minutes. (After adding the wine, lean close to the pan and breathe the aroma. You will be able to smell the raw alcohol. Breathe in several times during the cooking process, and as the alcohol evaporates and the rice begins to toast, the raw alcohol smell will dissipate and be replaced with the smell of toasted rice.)
Step 3When the liquid has been absorbed, stir again to finish toasting the rice. The rice should not brown, but it will separate into individual grains, looking much as it did before the wine was added. Scrape the bottom of the pan to keep the rice from sticking. The alcohol smell should be completely gone. Increase the heat to medium and add just enough stock to cover the rice, and salt to taste. When it boils, reduce the heat and simmer for 4 minutes.
Step 4Continue to cook, stirring frequently, letting the rice cook almost completely dry before adding more stock, 1/2 cup at a time. Taste the rice from time to time. The liquid should continue to simmer throughout the cooking process. The finished rice will be similar to al dente pasta; it should be thoroughly cooked but with a little "bite" remaining to it, never mushy. This process should take about 15 minutes. The rice will be drier and "tighter" than risotto normally would be. It should look a bit pasty.
Step 5Remove the risotto from the heat and, using a wooden spoon, beat in the butter a little at a time, working quickly so it will emulsify with the rice, creating a creamy risotto. Vigorously beat in the whipped cream, the Parmigiano-Reggiano and salt to taste.
Step 6Using a wooden spoon, fold the mascarpone into the risotto; add the basil, chives, parsley and lemon juice to taste, about 1 tablespoon. Adjust the seasoning as necessary. Pass the risotto mixture through a meat grinder with the smallest die attachment, and cool. (If you do not have a meat grinder, you can finely chop the stuffing with a knife.)