Preheat oven to 375ºF. Coat a 2-quart rectangular, round or oval baking dish with cooking spray.
In a large bowl, combine rice, salsa and cumin. Spoon 2 cups of rice mixture into prepared baking dish and spread out to evenly cover bottom of dish.
In another large bowl, combine refried beans, corn, chili peppers and chili power. Using a rubber spatula, scrape bean mixture on top of rice layer and smooth out top.
Squeeze out any excess water from spinach or collard greens and then spread on top of bean layer; sprinkle with 6 tablespoons of cheese. Top with remaining rice mixture and smooth out top; sprinkle with remaining cheese.
Place casserole on a large rimmed baking sheet to catch any spillage. Bake until heated through and cheese is browned and bubbling, about 30 minutes. Sprinkle with cilantro (if desired), cut into 6 pieces and serve.