Wash and thinly slice potatoes.
Melt butter in pan and slowly add in flour about 1/4 cup at a time until you achieve a thick paste like consistency. Mix in salt and pepper to taste.
Slowly mix in milk about 1/4 cup at a time mixing well until you have a nice creamy consistency.
Add cheese and stir over low/medium heat until pretty much melted/incorporated, but be careful not to let your sauce burn or stick to the bottom of the pan.
Coat bottom of dish with sauce. Add a layer of potatoes. Add another layer of sauce and then another layer of potatoes. Pour the rest of the sauce to cover the top of the dish.
Top with fresh chopped lemon thyme and parsley.
Cover and bake at 350 degrees for 30 minutes. Uncover and bake another 30 minutes or until fork tender.