Preheat oven to 425° F
Heat the butter and add the onion to the pan. Cook until the onion is softened and translucent. Cook for 30 seconds. Add the garlic, salt and pepper. Bring to a simmer the stock, cream, potatoes, and reduce heat. Reduce heat to medium-low, cover, and simmer the potatoes gently for 15 to 20 minutes. Season to taste. Gently stir.
Transfer the mixture to an 8x8'' baking dish or similar size, or to five to six individual casseroles. Bake the casserole in the oven for 10 to 15 minutes (or less for individual casseroles). Let cool for a few minutes before serving. Sprinkle with chopped parsley.
This is a creamy dish that our family loves, even though it is simple. It has cream, potatoes, cheese, cream, and a small amount of onion, garlic, and a bit of chicken stock to add flavor. You can taste the sauce before adding it to the casserole. Season the dish with salt and pepper. If you prefer a more flavorful dish, increase the amount of onion and garlic.