- Preheat oven to 400 degrees Fahrenheit. Grease a 9″ x 13″ casserole dish with butter or cooking spray.
- Thinly slice russet potatoes, rinse them in bowl of water and pat completely dry.
- In a large skillet over medium heat, melt butter. Add minced garlic cloves. Sprinkle flour in and mix for about 2 minutes.
- Add chicken or vegetable stock to the mix. Add salt, pepper, and dill spice mix.
- Whisk until mixture becomes thick. Slowly add milk in batches, stirring in-between. Take off heat.
- In the baking dish, evenly lay out 1/3 of the sliced potatoes, topping them with the mixture. Add a light layer of feta cheese crumbles. Repeat two more times with the potatoes and mixture.
- Bake on center of baking rack for 30 minutes. Remove and add final thick layer of feta cheese. Cook for another 5 minutes.
- Remove from oven and let rest for 10-15 minutes. Top with fresh thyme. Enjoy!