Preheat oven to 350 degrees.
Place chopped sweet potatoes in a large pot and cover with enough water to cover potatoes completely.
Bring to a boil of medium high heat and continue to cook for about 15-20 minutes until potatoes are fork tender.
Drain and transfer potatoes to stand mixer or a large bowl. Add oil, salt, cinnamon, nutmeg, and syrup if using. Whip until fluffy and lump free.
Combine topping ingredients in a bowl and mix to combine thoroughly.
Spread potatoes in an even layer in an 8 x 8 baking dish.
Spoon topping over potatoes in an even layer.
Bake for 30 minutes until topping is caramelized and has browned slightly.