Step 1

Place 5 cups broth in a medium saucepan over low heat and keep it at a very low simmer. While it is heating, finely chop 1 yellow onion. Finely grate 3 ounces Parmesan cheese (about 3/4 cup). If not using chopped spinach, break up 1 (10-ounce) package frozen spinach into small pieces.

Step 2

Heat 2 tablespoons of the olive oil in a large, high-sided sauté pan or Dutch oven over medium heat. Add the onion and cook until soft and translucent, about 5 minutes. Add 1 1/2 cups rice and cook, stirring occasionally, until toasted and fragrant, about 3 minutes. Season with kosher salt and black pepper. Add 1/2 cup dry white wine if using and cook until reduced by half, about 3 minutes.

Step 3

Add the broth 1/2 cup at a time, stirring frequently. Wait until the broth has been almost completely absorbed by the rice before adding the next 1/2 cup. Cook until the rice is al dente and the broth is creamy, 16 to 18 minutes total (you might not use up all of the broth). If you run your spatula through the risotto, the risotto should flow slowly to fill in the space. Stir in the spinach and cook over low heat until warmed through, about 1 minute.

Step 4

Remove from the heat. Stir in the Parmesan and remaining 1 tablespoon olive oil. Taste and season with salt and pepper as needed. Serve immediately, garnishing each bowl with more grated Parmesan.