Sweet Potato and Apple Casserole

6 large sweet potatoes, peeled, sliced, and boiled until tender-crisp.
6 tart apples, peeled, and sliced
1/2 cup of butter (or more to taste)
1/2 cup of brown sugar (or more to taste)

Preheat the oven to 350 degrees F.

Butter a casserole.

Layer potatoes into the casserole, dot with some butter, and sprinkle with some brown sugar.

Cover the potato layer with some sliced apple.

Repeat.

End with a layer of potatoes, butter, and brown sugar.

Bake 30 to 45 minutes, until the potatoes are tender and browned, perhaps 8 to 10 minutes.