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

Add the minced garlic and cook for another minute until fragrant.

Stir in the Arborio rice and cook for 2-3 minutes, stirring frequently until the rice is lightly toasted.

Pour in 1 cup of the warm vegetable broth and stir until the liquid is absorbed.

Continue adding the broth, one ladle at a time, stirring frequently and allowing the liquid to absorb before adding more.

After about 15 minutes, add the asparagus pieces and continue cooking until the rice is creamy and al dente, about 5-7 minutes more.

Stir in the grated Parmesan cheese and season with salt and pepper to taste.

Remove from heat and let it sit for a couple of minutes before serving.