Heat the broth in a saucepan over medium heat.
Meanwhile, heat the olive oil in a large pot or dutch oven over medium-high heat. Once heated, add the onion, mushrooms, garlic, salt, pepper and fresh thyme leaves. Cook, stirring, until the mushrooms are tender; about 5 minutes.
Add the rice to the pot and stir to toast the rice until fragrant; about 2 minutes.
Next, add the white wine and continue to cook stirring until the wine is absorbed.
Once the wine is absorbed, with a ladle add one cup of the warm broth to the risotto and continue to cook stirring until the broth is absorbed fully.
Continue to ladle the broth one cup at a time, allowing the rice to absorb most of the liquid before adding more. This process should take 25-30 minutes (and you should use all or almost all of the warm broth from the saucepan). Your rice should be tender and creamy.
Add the grated parmesan and stir one more until combined.