Preheat oven to 350 degrees F (175 degrees C).

Lightly butter a casserole dish.

In a small skillet, melt 1/4 cup butter over medium heat.

Add chopped onion to the skillet and cook for 3-4 minutes, or until softened.

Pour the cooked onion and butter mixture into a large bowl.

Add sour cream, cream of celery soup, shredded monterey jack and cheddar cheese blend, garlic powder, thawed frozen hash brown potatoes, salt, and black pepper to the bowl.

Combine all ingredients in the bowl until well blended.

Pour the mixture into the prepared, buttered baking dish.

Top evenly with crushed potato chips.

Bake in the preheated oven for 45 minutes, or until hot and bubbly.