Peel and slice potatoes to measure 6 to 7 cups.
Place in a large bowl of water as you go along slicing. This will keep the potatoes from turning brown.
Melt the dairy free butter in a large saucepan.
Add the flour and stir over medium-heat for a few minutes. Keep stirring so that it is all blended well.
Pour in the dairy free milk.
Bring to a low boil stirring often.
After the sauce comes to a boil turn down the heat to medium and cook until it is smooth and thickens a bit. About 10 to 15 minutes. Add salt and pepper and stir.
Layer the potatoes in a large 9" x 13" casserole dish, overlapping in a staggered type of style. This lets the sauce get down in between the nooks and crannies.
Pour the sauce all over the top. Cover with a lid or foil.
Bake at 350° for 30 minutes.
Uncover and bake another 60 minutes.
Remove from oven and sprinkle fresh herbs over the top.
Let stand for 10 minutes. The sauce will thicken.