Turn a 12-cup muffin tin upside down. Nestle 6 corn tortillas in the spaces between the cups to form 'bowls.' Bake in a preheated oven at 375 degrees F (190 degrees C) until warm and beginning to brown, 10 to 15 minutes. Transfer to a wire rack to cool.
Cook UNCLE BEN'S(R) READY RICE(R) Spanish Style according to directions on the package. While the rice is still warm, transfer to a large bowl and mix in black beans, corn, tomatoes, and 2 tablespoons cheddar cheese.
Fill the shells with the rice and bean mixture, then top evenly with remaining cheddar cheese. Add toppings like avocado, cilantro, or olives.