Preheat the oven to 350F. Lightly grease a 9X13-inch baking pan with cooking spray and set aside.
In a large dutch oven or pot, melt the butter over medium heat. Add the onion and cook until the onion is softened and translucent, about 5-6 minutes.
Stir in the gluten-free flour and cook, stirring constantly, for about a minute.
Combine the chicken broth and milk in a liquid measure and slowly whisk in the mixture.
Stir in the salt, pepper and thyme.
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. Add the sour cream and mix until combined.
Fold in the frozen hash browns until well combined.
Evenly spread the potatoes into the prepared 9X13-inch baking dish and top with the crushed potato chips.
Bake for 40-45 minutes, until hot and bubbly around the edges.
Let the potatoes rest for 10 minutes before serving. Enjoy!