Preheat the oven to 425 degrees F (220 degrees C). Grease an 8x8-inch baking pan.
Blend corn muffin mix with creamed corn, milk, and egg. Pour into the prepared pan.
Melt butter in a saucepan over medium heat. Add onion and cook until soft and translucent, about 5 minutes. Mix onion with sour cream, 1/2 cup Cheddar cheese, hot sauce, and dill.
Pour onion mixture into the baking pan and spread carefully over the cornbread layer with a spatula. Sprinkle remaining Cheddar cheese on top.
Bake in the preheated oven until top is golden brown, 25 to 30 minutes.
