Preparation of Ingredients: Begin by preparing your ingredients: shred the cheese and finely dice the red onion. Preheat your oven to a temperature of 375 degrees Fahrenheit, ensuring it is ready for baking.
Combining Ingredients: In a substantial mixing bowl, combine the sour cream, mayonnaise, all seasonings (garlic powder, chili powder, salt, and pepper), finely diced red onion, diced green chilies, and frozen corn. Integrate most of the shredded cheese into this mixture, reserving approximately 2/3 cup for later use. Stir the mixture thoroughly to ensure all ingredients are evenly distributed and the mixture is uniform in consistency. Taste the mixture and adjust seasoning as necessary.
Assembling the Dish: Spray an 8x8-inch baking dish with nonstick cooking spray. Transfer the mixture to the prepared baking dish, spreading it evenly with a spatula. Sprinkle the reserved cheese evenly over the top of the mixture.
Baking: Place the dish in the preheated oven and bake for 20 minutes, or until you observe that the edges have started to bubble vigorously and the cheese has turned golden brown in color. This dip is optimally served warm, accompanied by tortilla chips for dipping.