1. Preheat oven to 375 degrees F. Begin by preparing the sauce according to instructions on package. While sauce is heating on stove, begin heating refried beans in another pan.
2. As beans get hot, and as sauce is thoroughly mixed, add about 1/4 cup sauce to the beans. You don't want the beans to be soupy, but this will make it more manageable.
3. Steam the spinach until wilted. Add corn and the chilies to the bean mixture. When spinach is finished, begin making the enchiladas.
4. Spread approximately 3 tablespoons sauce on each flat tortilla, then layer bean mix, spinach and a small amount of cheese (if using) in the center of the tortilla. Roll up and place in a baking dish.
5. Line up enchiladas in baking dish, then cover with remaining sauce and any leftover cheese. Bake covered with foil for 20 minutes. Bake an additional 10 minutes, uncovered.