Rehydrate the porcini mushrooms in warm water. Heat olive oil and sweat the onions until translucent. Add the rice and stir to coat with oil. Add 8 fluid ounces of the hot chicken stock. Stir and simmer until all of the liquid has been absorbed.
Add 1 quart of stock in 8 ounce increments. Season with salt and pepper. Continue cooking until most of the liquid is absorbed and the rice is three-quarters of the way cooked. Spread the rice on a sheet pan and allow to cool. Refrigerate.
To finish the risotto, add the remaining 8 ounces of chicken stock and white wine and stir over low heat until the rice is fully cooked. Fold in the re-hydrated mushrooms, butter, cheese, and basil. Adjust seasonings, if necessary.