First, preheat the oven to 350℉.
Add the thawed, drained corn to a large bowl or directly to a 9×13-inch baking dish.
Add the mayonnaise, sour cream, 2 tablespoons cilantro, salt, and garlic powder. Stir until the corn is evenly coated.
Spread the mixture evenly in the baking dish.
Bake uncovered for 40 minutes.
Remove from the oven and top with the crumbled cotija or queso fresco, Tajín, and additional fresh cilantro.
Allow the casserole to cool for a few minutes before serving hot or warm.