Preheat oven to 375F.
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, remove them from the pouch and let cool for a few minutes. When they're cool enough to handle, lightly rub the outside of them with a paper towel 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-high heat with 2 tablespoons EVOO, 2 turns of the pan, and butter. Add the onions and garlic, and saut 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 a third 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, about 5 minutes. Ladle another third of the remaining liquid and continue stirring the rice until that liquid has fully absorbed, 4-5 minutes. Ladle in half of the remaining stock and stir the rice another 4-5 minutes. Add in the beet puree and the rest of the stock and cook an additional 4-5 minutes, until the rice is al dente. Season with salt and freshly ground black pepper and stir in the 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.