Preheat oven to 375ºF.
Place the beets on a large piece of aluminum foil and drizzle with some EVOO. Season with salt and freshly ground black pepper and fold the foil into a pouch. Roast the beets inside the pouch until tender, about 45 minutes.
When the beets are done roasting, let cool for a few minutes then lightly rub the outside of them to remove the skins. Transfer the beets to a food processor and puree them until smooth. Reserve the puree until the risotto is finished cooking.
Bring the water and stock to a boil in a saucepot, then reduce heat to low to keep warm.
Place a large skillet over medium heat with 2 tablespoons EVOO, 2 turns of the pan, and butter. Add the onions and garlic, and sauté until the onions begin to get tender, 4-5 minutes. Add the arborio rice and toast it in the pan, stirring constantly with the veggies, 2-3 minutes more. Add wine or sherry and cook until the liquid has absorbed, 1 minute.
Ladle about half of the stock or broth into the pan with the rice and bring it up to a bubble, stirring constantly. Simmer the mixture, stirring frequently, until all the liquid is absorbed, 4-5 minutes. Ladle in about half of the remaining liquid and continue stirring the rice until that liquid has fully absorbed, 3-4 minutes. Ladle in the remaining stock and cook the risotto until most of the remaining liquid has been absorbed and the rice is al dente, 3-4 minutes. Season the risotto with salt and freshly ground black pepper and stir in the reserved beet puree and Parmigiano Reggiano.
Serve up the risotto immediately and garnish each plate with the chopped beet greens. Serve Spinach Garlic Bread alongside and pass additional Parmigiano Reggiano cheese at the table.