12 servings; MFP
907g; 2 pounds hash brown potatoes - defrosted (if using fresh, dice potatoes and boil or steam until tender)
43g; 3 tbsp unsalted butter
8g; 1 tbsp all purpose flour (was 1 can cream of celery soup)
170 g; 1.5 cups shredded cheddar cheese (8 oz)
230 g; 1/2 pint sour cream (updated; was 1)
1/2 cup chopped onion (updated; was 1/4)
60g; Guess 1/4 cup milk; until consistency is right
15g; 1/4 cup Panko bread crumbs
KCl
Preheat oven to 350F.
Mix all ingredients in a bowl and place in a 9x13 pan.
Sprinkle panko bread crumbs over potatoes.
Refrigerate overnight.
Bake uncovered (yes, really uncovered for the whole time; trust me) for 45 - 60 minutes.
(Do not cook in crockpot overnight; they turn into cheesy mashed potatoes).