In a saucepan, heat the vegetable broth over low heat and keep it warm.
In a large skillet, add olive oil and sauté the chopped onion over medium heat until translucent, about 3-4 minutes.
Add the minced garlic and sliced mushrooms to the skillet. Cook until the mushrooms have released their moisture and are golden brown, about 5-7 minutes.
Stir in the Arborio rice, toasting the rice in the skillet for about 2 minutes until it’s slightly translucent around the edges.
Begin adding the warm vegetable broth one ladle at a time, stirring frequently. Allow the rice to absorb the broth before adding the next ladle. This process should take about 18-20 minutes.
Once the rice is creamy and al dente, stir in the heavy cream and grated Parmesan cheese, mixing until everything is combined and creamy.
Season with fresh thyme, salt, and pepper to taste.
Remove from heat and let it sit for a minute.
Serve hot, garnished with fresh parsley and an extra sprinkle of Parmesan if desired.
Notes
For a richer flavor, use a mix of different mushrooms.