Bring a small pot with 4 cups of stock to boil. Turn heat to low to keep it at a simmer. In a second pot, heat some olive oil over medium heat. Add shallot and garlic and cook until aromatic. Add arborio rice and shredded beets and stir. Toast for 1 minute. Add a couple ladles of broth just to "veil" the rice. Stir, only adding more broth once the rice absorbs existing liquid. Continue process, adding broth a little at a time and stirring often, until rice is tender, 20-25 minutes.