Heat the olive oil in a large skillet over medium heat.
Add the diced onion and sauté for about 3-4 minutes until translucent.
Stir in the minced garlic and cook for an additional 1 minute.
Add the mixed mushrooms and sauté for about 5-6 minutes.
Stir in the Arborio rice and cook for 2-3 minutes until lightly toasted.
Slowly add the vegetable broth, one cup at a time, stirring constantly.
Reduce the heat to low, cover, and simmer for 18-20 minutes until rice is tender.
Remove from heat and let it sit, covered, for 5 minutes.
Fluff the rice with a fork, season with salt, and garnish with fresh parsley.