Place sweet potatoes in a large saucepan with water to cover them. Bring water to a boil, reduce heat, cover and let simmer 25 to 30 minutes until tender.
Preheat oven to 350 degrees F (175 degrees C).
Grease a 8×8 inch baking pan.
When the sweet potatoes are cool, peel and cut them into large chunks. Arrange them in the prepared pan.
In a small saucepan, melt butter, syrup, and brown sugar over a low heat. Cook for 3 to 5 minutes, stirring constantly.
Sprinkle syrup mixture over sweet potatoes. Top mixture with nuts. Sprinkle lightly with sea salt.
Bake 5 to 7 minutes, or until top is lightly browned.