In a saucepan, bring the vegetable broth to a simmer over medium heat. Keep it warm on the stove.
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and sauté until translucent, about 3-4 minutes.
Stir in the minced garlic and sliced mushrooms, cooking for an additional 5-6 minutes until the mushrooms are softened and browned.
Add the orzo pasta to the skillet, stirring for 1-2 minutes to lightly toast it.
Gradually add 1 cup of the warm vegetable broth to the orzo, stirring frequently until the liquid is mostly absorbed. Continue adding the broth, one cup at a time, stirring often until the orzo is cooked and creamy (about 10-12 minutes).
Once the orzo is tender, lower the heat and stir in the heavy cream and Parmesan cheese. Mix until well combined and creamy.
Season with salt and pepper to taste.
Remove from heat and let it sit for a minute to thicken slightly.
Notes
Serve in shallow bowls, garnished with fresh parsley and extra Parmesan.