In a medium saucepan, bring the vegetable broth to a simmer over low heat. Keep warm.
In a large skillet, heat the olive oil and butter over medium heat. Add the chopped onion and sauté until translucent, about 3-4 minutes.
Add the minced garlic and sliced mushrooms to the skillet. Cook for about 5-7 minutes, until the mushrooms are tender and golden.
Stir in the orzo pasta and cook for 1-2 minutes, allowing it to toast slightly.
Gradually add the warm vegetable broth, one ladle at a time, stirring frequently. Allow the orzo to absorb the broth before adding the next ladle. Repeat this process until the orzo is creamy and al dente, about 15-20 minutes.
Once the orzo is cooked, stir in the chopped spinach and grated Parmesan cheese. Season with salt and pepper to taste.
Cook for an additional minute until the spinach wilts down.
Remove from heat and let it rest for a couple of minutes, allowing the flavors to meld.
Serve the risotto in bowls topped with additional grated Parmesan and freshly chopped parsley for a pop of color.
Notes
Serve with extra Parmesan and parsley for garnish.