01 - 
                Preheat the oven to 375°F (190°C). Lightly butter a baking dish.
              
              
              
                02 - 
                Peel and thinly slice the potatoes. Arrange the slices in the prepared baking dish.
              
              
              
                03 - 
                In a saucepan over medium heat, melt the butter and whisk in the flour. Cook while stirring until smooth. Gradually whisk in the milk and cream, ensuring no lumps form. Season with onion powder, garlic powder, salt, and black pepper. Bring the mixture to a boil and then simmer until thickened, stirring occasionally.
              
              
              
                04 - 
                Stir in the mozzarella and cheddar cheese until melted and fully incorporated into the sauce.
              
              
              
                05 - 
                Pour half of the cheese sauce over the potatoes. Cover the dish with foil and bake for 30 minutes.
              
              
              
                06 - 
                Remove the foil and pour the remaining sauce over the potatoes. Bake uncovered for an additional hour or until the top is golden and the potatoes are tender.
              
              
              
                07 - 
                Garnish the dish with fresh parsley or dill. Serve hot or warm.