Cheesy Potato Casserole is a hot dish made with a creamy and cheesy potato mixture, topped and baked with corn flakes for that extra crunch.
Preheat oven to 350°F. Spray a 9x13-inch baking dish with nonstick spray.
In a large bowl, combine the potatoes, butter, shredded cheese, and sour cream. Mix well and set aside.
In a medium skillet over medium heat, melt butter.
Add onion and cook until translucent (3-5 minutes). Add the garlic and cook for one more minute.
Add flour, salt, pepper, cayenne pepper, and dry mustard. Cook another minute.
Slowly add milk, whisking until smooth.
Slowly add chicken broth, whisking until thickened.
Pour the sauce into the potato mixture. Mix well.
In a large, microwave-safe bowl, melt butter.
Add corn flakes. Toss to coat.
Pour the sauce and potato mixture into the prepared baking dish.
Top dish with the butter and corn flakes topping.
Bake 40-50 minutes, or until golden brown and bubbly.
Remove from oven. Let it rest a few minutes before serving.