In a saucepan, heat olive oil over medium heat. Add chopped onion and sauté until translucent.

Add Arborio rice and stir for 1-2 minutes until the rice is lightly toasted.

Gradually add warm vegetable broth, one ladle at a time, stirring frequently until absorbed.

Once the rice is creamy and al dente, stir in the asparagus, peas, and spinach.

Cook for an additional 5 minutes, then remove from heat and stir in grated Parmesan cheese.

Season with salt and pepper to taste, and serve warm.