Heat olive oil and butter in a large pan over medium heat. Add diced onion and cook until translucent.

Add minced garlic and sliced mushrooms; cook until mushrooms are browned.

Stir in arborio rice and cook for 2 minutes to toast the rice.

Pour in white wine and stir until absorbed.

Gradually add vegetable broth, one ladle at a time, stirring constantly until absorbed before adding more. Repeat until rice is creamy and tender, about 20 minutes.

Stir in grated Parmesan cheese and adjust seasoning as needed. Serve hot.