Rinse the Brussels sprouts under cold water. Remove the out leaves and stem, and cut into halves. Set to the side.
Boil the Brussels sprouts for for 2-3 minutes. With a slotted spoon, remove to a bowl to stop cooking.
Keep the remaining water warm over a low flame.
In a large skillet, over medium heat, sauté the onion in the olive oil until translucent. Add the pancetta and allow to get golden brown, but not crispy. Add the rice and stir together until opaque and lightly toasted. Add the wine and let evaporate, and then add a ladle of the warm water. Continue to cook and stir (preferably with a fork) until the liquid is almost fully absorbed. As the liquid absorbs, add more stock, a ladle at a time, waiting until almost completely absorbed before adding more. Add the Brussels sprouts with the last ladle of stock that is required. Cook until rice is al dente, about 10-15 minutes. (You may not need to use all of the stock, depending on how quickly it absorbs.)
Mix in the cheese. Remove the skillet from the heat. Serve immediately with some fresh black pepper.