3 T butter
1 large yellow onion, chopped
1/4 C flour
1 1/2 C low-sodium chicken broth
1 C milk
1 1/2 tsp salt
1/2 tsp pepper
1/2 tsp dried thyme
2 C shredded sharp cheddar cheese (8 ounces)
26-oz bag frozen shredded hash browns
1/2 C light sour cream
3 C cornflakes, lightly crushed
2 T butter, melted
Melt the butter in a large pot over medium heat. Add the onion and cook until the onion is softened and translucent about 5-6 minutes. Stir in the flour and cook, stirring constantly, for about a minute. Combine the chicken broth and milk in a liquid measuring cup and slowly whisk in the mixture. Add the salt, pepper and thyme. Stir to combine. bring the mixture to a boil and then reduce the heat to medium-low and simmer, stirring frequently, until the mixture is slightly thickened, about 5 minutes.
Take the pot off the heat and stir in the cheese until smooth. Mix in the frozen hash browns, lifting and folding the mixture until well combined. Finally, stir in the sour cream.
In a medium bowl, toss the lgithly crushed cornflakes with the butter util evenly combined. Scoop out the potato mixture into a 9X13 inch baking dish and top with the buttered cornflakes. Bake at 350 degrees for 45 minutes, until hot and bubbly around the edges. Let the potatoes rest for 10 minutes before serving.