Preheat the oven to 350°F.

Spray a 9x13-inch baking dish with nonstick cooking spray. Set aside.

Place the corn kernels, cooked rice, salsa, sour cream, scallions, cumin, garlic powder, salt, black pepper, and shredded cheese in a large mixing bowl. Fold the ingredients together with a rubber spatula until thoroughly combined.

Transfer the mixture to the prepared baking dish and smooth it into an even layer. Sprinkle the shredded cheese evenly over the top.

Bake the casserole on middle rack of oven until cheese is golden brown and dish is gently bubbling at the edges, 35-40 minutes.

Check to see that casserole is done. Remove from oven or add time as needed.

Allow the casserole to rest for 15 minutes before serving.