Yukon Potatoes Butter Onion Garlic Cloves All-Purpose Flour Milk Chicken Broth Thyme Cheddar Mozzarella Parmesan
Clean potatoes, then thinly slice into 1/8 inch thin slices. Sauté onion and garlic in butter for a few minutes until they are soft and fragrant. Add flour and stir to combine. Once combined, add milk, chicken broth, thyme and salt.
Whisk mixture continuously as it comes to a boil so that the flour clumps dissolve. Continue stirring and cook until sauce thickens slightly. Turn off heat and add shredded cheddar, mozzarella and parmesan. Stir to combine.
Next, layer the potatoes and cheese sauce. There should be three alternate layers of potatoes and cheese sauce. Cover casserole with aluminum foil, bake at 350°F for 60-75 minutes.