In a large skillet, melt 4 tbsp butter over medium-high heat. Add chopped shallots and stir to coat. After 1-2 minutes, add the chopped fresh thyme and stir to coat. Cook until shallots have slightly softened, about 5-6 minutes.
Add the remaining 4 tbsp butter and the mushrooms to the skillet, then toss so the mushrooms are thoroughly coated. Stir in the lemon juice, soy sauce, and black pepper mixture and toss so all mushrooms are coated with the sauce. Let cook 6-8 minutes, until the mushrooms are tender.
Taste the mushrooms; if too lemony, add a little more soy sauce, and vice versa. Once you’re satisfied with the flavor, move on to making the risotto.
Reduce the skillet heat to medium. Pour the Arborio rice into the skillet and stir into the mushrooms. Cook 1-2 minutes, then stir in the white wine, deglazing the bottom of the skillet as you go. Cook a few minutes, stirring regularly, until the wine is almost totally absorbed.
Ladle in ½- ¾ cup of the simmering chicken broth into the skillet, pouring enough in so it just covers the rice. Stir and let cook, stirring regularly, until liquid is almost totally absorbed. Then add in another ladle of chicken broth.
Repeat the "add-broth-stir-until-liquid-absorbed" process, adding more broth whenever the pan starts to get dry. Be patient – this will take 30-40 minutes.** SEE BELOW FOR RISOTTO COOKING TIPS.
Once the risotto is cooked through, turn off the heat under the skillet and the pot that held the chicken broth. Stir the grated cheese into the skillet. Taste and adjust seasoning as desired.
Serve mushroom risotto immediately, garnishing with more grated cheese and chopped parsley if desired.