Combine the garlic with the onions after smashing and mincing it. Toss and cook until a pleasant aroma emerges.
Toss the onions with the flour and mix well. After a brief period of stirring, gradually pour in the chicken stock while continuing to stir. Also, while swirling, slowly pour in the milk.
Allow the ingredients to come to a boil and begin to thicken.
Coat with cheese, sour cream, salt, and pepper. As the cheese melts, let the mixture to simmer and thicken. You can tell whether there's enough spice by tasting it.
Combine with parsley.
After the casserole dish is ready, combine the hash browns and cheese sauce in a big bowl. Be careful to distribute it evenly.
Once the dish has browned and bubbled around the edges, sprinkle with more cheese and bake for 35 to 40 minutes.
