First time I made this. Here's the recipe (which I doubled)

Four medium size sweet potatoes
Two Granny Smith apples (I used Golden Delicious - they get rather soft)
1/4 cup maple syrup
2 tablespoons olive oil
1/2 teaspoon cinnamon
1 cup walnuts (I doubled the recipe but kept the nuts to 1 1/2 cups and used pecans instead)

Peel, slice and quarter sweet potatoes
Peel, core and chop apples (I used one of those push down apple wedge slicer and cut each wedge in half.)
Place potatoes and apples in a large greased baking dish (the standard size Pyrex bowl works fine for this amount)
Sprinkle apples and potatoes with cinnamon and then pour oil and syrup over them. Mix well and place walnuts (or other nuts) on top. (You might want to pour about 1 teaspoon of syrup over nuts for a glazed effect.)
Cover dish at bake 1 hour + 20 minutes at 350° until potatoes are tender.