Preheat the oven to 350 °F.
Cook the rice according to the instructions on the package. I usually cook the rice the night before to save time. Cut the bell peppers into bite-sized chunks.
Heat some oil in a large pan and sauté the bell peppers for about 3 minutes. Then add the garlic and cook it for another minute. Add the rice, the tomato paste, and the spices. Cook for 2 minutes, then add the black beans and the canned tomatoes. Cook for 2 minutes. Season with salt, pepper, and red pepper flakes.
Fill into a casserole dish. Crumble the nacho chips with your hands and sprinkle them on top of the rice. Then make the cheese sauce: Combine the cashew butter with the water and whisk until well combined. Season with red pepper flakes. Pour the cheese sauce over the casserole and bake it for 10 minutes.
Once the rice casserole comes out of the oven, sprinkle it with cilantro or parsley, green onions and serve it with avocado. I love to drizzle some fresh lime juice on top. Enjoy!