Bring the stock to simmer in a medium sauce pan, reduce the heat to low, and keep hot.

Heat the olive oil in a heavy large sauce pan over medium heat, add the chopped shallots and garlic, saute for one minute.

Add the mushrooms, and cook until they are tender and the juices are released, about 8 minutes.

Add rice and stir to coat. Add the sherry until the liquid is absorbed. Increase the heat to medium-high, then start adding the stock one cup at a time and stir until it's absorbed.

Continue until the rice is just tender and creamy, about 20 minutes. Stir in the Parmesan cheese and the fresh thyme.