Preheat oven to 350 degree F.

With 2 Tablespoons of butter, saute onions and pepper until the onions are transparent. Add the mushrooms to onions and peppers and saute until soft.

Add the sauted vegetables to the thawed hash browns in a large bowl. Add the remaining butter, cream of chicken soup, sour cream and cheddar cheese. Salt and pepper to taste.

Put into a greased or non-stick sprayed 11 x 14 inch casserole dish. Top with the Panko bread crumbs. I like to spray butter flavored non-stick spray on the panko crumbs. Bake for 45 minutes, or until casserole is bubbly and the panko crumbs are golden brown.