Heat the olive oil in a large skillet over medium heat. Add the chopped onion and sauté for 3-4 minutes until translucent.
Add the minced garlic and sliced mushrooms to the skillet. Cook for another 5-6 minutes, stirring occasionally, until the mushrooms are soft and slightly golden.
Stir in the Arborio rice and thyme to coat the rice grains with the oil and cooking flavors, cooking for about 2 minutes.
Pour in the vegetable broth and bring to a gentle simmer. Cover the skillet with a lid and allow the rice to cook for about 15 minutes, stirring occasionally, until most of the liquid is absorbed and the rice is creamy.
Lower the heat and add the cream cheese, stirring until completely melted and incorporated into the rice. If using Parmesan cheese, add it at this point for an extra creamy texture.
Fold in the fresh spinach, cooking until just wilted. Season with salt and pepper to taste.
Remove from heat, and let sit for a few minutes to meld flavors.
Serve warm, garnished with chopped parsley on top.
Notes
Feel free to use any variety of mushrooms and adjust the seasoning to your taste.