Preheat the oven to 350?F.
Heat the olive oil in a large saucepan or Dutch oven over medium-high heat. Add the onions, bell peppers, and jalapeŇos and cook, stirring, until soft, about 4 minutes. Add the garlic and cook for 1 minute. Add the rice and cook, stirring, until opaque and nutty in aroma, 2 to 3 minutes. Add the chicken broth, tomatoes, salt, Southwest Essence, and saffron, if using. Stir well and bring to a boil. Cover with a tight-fitting lid and transfer to the oven. Bake until the rice is tender and the liquid is absorbed, 25 to 30 minutes.
Remove from the oven and let sit, undisturbed, for 5 to 10 minutes. Fluff the rice with a fork and stir in the green onions and cilantro, if desired. Serve hot.
Makes about 10 cups, 10 to 12 servings