Crockpot Hashbrown Casserole (NO cream of soups)

Ingredients

• 1/4 cup finely chopped mushrooms
• 1/2 cup sour cream, I used reduced-fat
• 3 tablespoons flour
• 3 tablespoons butter
• Salt and pepper (I used about 1 tsp. salt and a heaping 1/4 tsp. pepper)
• Optional toppings: Cooked and chopped bacon, fresh parsley
• 1/4 teaspoon garlic powder
• 1 package (20 ounces) Simply Potatoes shredded hashbrowns
• 3/4-1 cup freshly shredded sharp cheddar cheese
• 1/4 cup finely chopped yellow onion
• 1 cup milk, I used 1%