In a large saucepan, heat the stock and water to a simmer. Keep warm.
In another large saucepan, heat the EVOO, 2 turns of the pan. Stir in the onion and garlic until fragrant, about 5 minutes. Stir in the sage and thyme; season with salt and pepper. Stir in the rice to toast for a minute or two. Stir in the wine and cook to evaporate completely. Now begin adding the stock, 11/2 cups at a time, adding more liquid as it evaporates and stirring to develop the starches in your risotto with each addition. It should take 18 minutes on the nose from the first addition of stock to cook the risotto to al dente.
Just as the risotto is done, stir in the walnuts, cheese and butter; season with salt and pepper. Serve immediately.