Risotto Alla Primavera

Name: Risotto Alla Primavera
Ingredients: 6 1/2 cups (about) vegetable broth; 3 tablespoons unsalted butter, divided; 1 tablespoon extra-virgin olive oil; 1 8-ounce onion, chopped; 1 medium leek (white part only), sliced crosswise into thin rings; 2 stalks green garlic, chopped, or 1 garlic clove, minced; 2 cups arborio rice or carnaroli rice; 1/2 cup dry white wine; 1 cup 1-inch pieces thin asparagus; 1 cup freshly shelled small peas or petite frozen peas (about 1/4 pound); 1/4 cup chopped fresh Italian parsley; 3/4 cup freshly grated Parmesan cheese, plus additional for serving