Melt a bit of butter in a pan and sauté the onion over low heat until it starts to become translucent, stirring constantly to prevent burning.
Add the rice to the pan and toast it until the grains begin to appear translucent, stirring constantly.
Pour in 1 ladle of broth and mix well. Cook the risotto over medium-low heat, stirring occasionally and adding more broth as needed to keep the rice from drying out.
Meanwhile, peel and grate the beets using a medium grater. Wash the thyme, dry it, and remove the leaves from the stems.
After 10 minutes, add the grated beets and thyme leaves to the pan with the rice. Mix well, and continue cooking.
When the rice is cooked, turn off the heat. Add grated cheese and butter to taste. Stir well until the butter melts.