Preheat oven to 400°F. Coat a 9-by-13-inch baking dish with cooking spray.
Heat oil in a large nonstick skillet over medium heat. Add sweet potatoes; cook, stirring occasionally, until just tender on the outside, 10 to 12 minutes. Add chili powder, cumin, salt and pepper; cook, stirring constantly, until fragrant, about 30 seconds. Stir in tomatoes and green chiles; cook, stirring occasionally, for 1 minute. Remove from heat; stir in black beans, corn and ¾ cup cheese.
Transfer the mixture to the prepared baking dish. Scatter the remaining ½ cup cheese on top. Cover the baking dish with foil; bake for 15 minutes. Remove the foil; bake until the sweet potatoes are tender and the cheese is melted and bubbly, 8 to 10 minutes. Top with scallions and cilantro. Serve with lime wedges.
