Preheat oven to 350 Degrees. In a medium skillet, melt 2 tbsp of butter and saute the onions until translucent. Add in the minced garlic until fragrant. Remove from the skillet and set aside. Cook the bacon and cut it into bite pieces.
In a large bowl mixed together the hash brown, onions, garlic, bacon, condensed cream of chicken soup, sour cream, parmesan cheese, 1 cup cheddar cheese, salt, and black peppers.
Spread the mixture into a 9×13 baking pan. Add the remaining cheese on top.
Melt the 4 tbsp of butter and mix the cornflakes with the panko bread crumbs in a bowl. Spread the cornflakes and bread crumbs on top of the pan evenly.
Bake for 60 minutes or until cooked.