Thinly slice potatoes and layer with onion in greased baking dish. Mix oil and melted butter (Butter is optional) with garlic, bay leaf, thyme, paprika, salt and pepper. Evenly cover the potatoes with it. Pour stock down the sides of the dish so as not to disturb the seasonings. Bake in preheated oven at 375 degrees about 1 hour or bake covered for 40 minutes and then 20 minutes more for browning the top.