Step 1

Preheat oven to 350 and grease a 9x13 casserole baking dish.

Step 2

Preheat medium pot over medium heat on stove-top.

Step 3

Add oil, heat it through and add onions. Saute onions until they start to brown.

Step 4

Smash and mince garlic and add it to the onions. Stir and saute until fragrant.

Step 5

Sprinkle flour over the onions and stir well. Stir for a few seconds and start slowly pouring in chicken stock, while stirring. Pour in milk after that while stirring as well.

Step 6

Let the mixture heat through and start to thicken.

Step 7

Stir in sour cream, cheese, salt, and pepper. Let the mixture cook and thicken as the cheese melts. Taste to make sure you have enough seasoning.

Step 8

Stir in parsley.

Step 9

Mix hash browns and cheese sauce in a large bowl and spread the mixture in the prepared casserole dish. Make sure it's all spread evenly throughout.

Step 10

Spread some more cheese on top and bake for 35-40 minutes, until casserole browned and bubbles around the edges.