Mix-ins: sauteed mushrooms, spring vegetables, seafood, etc. cut small
Heat 3 tablespoons butter or olive oil in large saucepan over medium heat. When foaming subsides, add remaining 1 cup onions and 1/4 teaspoon salt; cook, stirring occasionally, until onions are softened and translucent, about 9 minutes.
Add rice and cook, stirring frequently, until grains’ edges are transparent, about 4 minutes. Add wine and cook, stirring frequently, until rice absorbs wine.
Add 3 1/2 cups broth and cook, stirring every 2 to 3 minutes, until liquid is absorbed, 9 to 11 minutes.
Stir in additional 1/2 cup broth every 2 to 3 minutes until rice is cooked through but grains are still somewhat firm at center, 10 to 12 minutes (rice may not require all of broth).
Stir in any mix-ins (and any accumulated juices), Parmesan, and chopped parsley. Adjust seasoning with salt and pepper; serve immediately in warmed bowls.