1. In a small saucepan, combine broth with 1 cup water. Bring to a boil; reduce heat, and keep at a bare simmer.

2. In a large saucepan, heat 2 tablespoons butter over medium. Add onion; season with salt and pepper. Cook, stirring occasionally, until onion is softened, 4 to 5 minutes. Add rice, and cook, stirring frequently, 2 minutes. Add wine, and cook, stirring occasionally, until absorbed, 1 to 2 minutes.

3. Add 2 cups hot broth; simmer over medium-low, stirring occasionally, until mostly absorbed, 10 to 12 minutes. Continue adding broth, 1 cup at a time, allowing each to be absorbed before adding the next, stirring occasionally, until rice is creamy and just tender, 20 to 25 minutes total (you may not need all the broth).

4. Remove from heat. Stir in Parmesan and remaining 2 tablespoons butter; season with salt and pepper.

1. MILANESE: In step 1, add saffron to broth mixture. In step 3, after adding last cup of broth to risotto, stir in peas.

2. TOMATO: In step 1, replace broth mixture with tomato juice and 2 cups water.

3. MUSHROOM: At the beginning of step 3, in a separate skillet, cook mushrooms with butter over medium-high until browned, 10 to 15 minutes. Proceed with step 3, and after adding last cup of broth to risotto, stir in cooked mushrooms.

4. SEAFOOD: In step 1, replace broth with clam juice and 2 cups water. At the end of step 3, a few minutes before risotto is done, stir in scallops and shrimp. In step 4, omit the Parmesan.