Heat the oven to 350 degrees and grease a baking dish that measures 9 by 13 inches.

Heat a medium pot on the stove over medium heat.

Put oil in a pan, heat it up, and then add the onions. Cook the onions until they turn golden brown.

Crush and chop garlic, then mix it with the onions. Mix and cook until it smells good.

Put flour on top of the onions and mix them together. Stir briefly and then slowly pour in the chicken broth while continuing to stir. Add milk while stirring.

Allow the mixture to warm up and begin to thicken.

Add sour cream, cheese, salt, and pepper and mix well. Allow the mix to cook until the cheese melts and thickens. Try the food to check if it has enough seasoning.

Add parsley and mix.

Combine grated potatoes with melted cheese in a big bowl, then spread the mix in the baking dish. Ensure that everything is evenly distributed.

Put more cheese on top and bake for 35-40 minutes until the casserole is golden brown and bubbles around the edges.

Enjoy!