Preheat oven to 375 F.
In a 9-inch cast iron skillet or oven proof pan, heat your oil over medium heat. Add the onion and saute until tender, about 4 to 5 minutes. (If using frozen corn, add corn now and cook until kernels are charred.) Add garlic and saute until fragrant, another 1 minute.
In a medium bowl, mix cream cheese, 3/4 cup cheese, mayonnaise and chili powder. Add corn mix and stir to combine.
Transfer mixture back into cast-iron skillet and spread into an even layer and sprinkle with remaining 1/4 cup of cheese.
Bake in the oven until edges are bubbling, about 12 to 15 minutes. Remove from the oven and sprinkle with cilantro and serve with corn chips.
