1. Place sweet potatoes in a large saucepan with enough water to cover. Bring to a boil and cook 25 minutes, or until tender but firm. Drain, cool and cut into 1/4 inch slices.
2. Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 7×11 inch baking dish.
3. In a small bowl, mix brown sugar, cinnamon and nutmeg.
4. Layer sweet potatoes, brown sugar mixture and apples in the prepared baking dish.
5. In a medium bowl, mix flour, brown sugar, butter and pecans. Sprinkle over the sweet potatoes.
6. Bake in the preheated oven 30 minutes, or until lightly browned.