1. Prep & Sauté
- Preheat oven to 350°F (175°C) and grease a 9×13-inch baking dish.
- Heat olive oil in a medium pot over medium heat.
- Sauté diced onion until lightly browned, then add garlic and cook for 1 minute until fragrant.
2. Make the Sauce Base
- Sprinkle flour over the onions and stir to coat.
- Gradually pour in chicken stock while stirring to form a smooth mixture.
- Slowly add milk, continuing to stir until fully combined.
3. Finish the Sauce
- Allow the mixture to thicken over heat.
- Stir in sour cream, 1 cup of shredded cheese, salt, and pepper.
- Cook until the cheese melts and sauce is creamy.
- Stir in minced parsley and adjust seasoning if needed.
4. Combine & Bake
- In a large bowl, mix the thawed hash browns with the cheese sauce until evenly coated.
- Spread the mixture in the prepared casserole dish.
- Top with the remaining 1 cup of shredded cheese.
- Bake 35–40 minutes, until the casserole is golden and bubbling around the edges.
