Step 1Wash the spinach leaves and remove the stems. Place them in a bowl and microwave on high until thoroughly cooked, about 2 minutes. Place the leaves in a blender container and add 1/2 cup of broth. Blend until pureed. Pour into a 1-quart measure and add more broth, or water, to equal 3 cups.
Step 2Heat the oil in a Dutch oven over medium heat. Add the rice and cook until fragrant and the rice changes color slightly, about 5 minutes. Add the onion and garlic and cook until the onion starts to soften, about 3 minutes. Add the corn kernels, the spinach mixture and 1 to 1 1/2 teaspoons of salt. Bring to a boil, reduce the heat, cover and simmer gently until the liquid is absorbed, 10 to 15 minutes. Reduce the heat to very low, using a heat diffuser if necessary, and let steam 15 minutes. Fluff with a fork before serving.