Preheat oven to 400 degrees. Clean sweet potatoes and prick a few holes around the surface of the potatoes with a fork. Wrap them in foil and place in a pan or baking dish. Roast in the oven for 1 1/2 hours; or until tender. Remove from the oven and allow to cool for at least 30 minutes before removing the skin.
Turn the oven to 350 degrees and prep a 9x9 pan with cooking spray. Add sweet potatoes to a bowl, and mash until smooth. Combine melted butter, brown sugar, granulated sugar, milk, vanilla, syrup and cinnamon until well combined. Then mix in eggs. Add sweet potato mixture to the prepared baking dish and set aside.
In a small bowl, combine flour, brown sugar, cinnamon, chopped pecans, salt and melted butter. Mix well. Scatter the pecan topping on top of the sweet potatoes.
Bake on the middle rack for 30-40 minutes until the topping is golden. Remove from the oven, allow to cool before serving. Enjoy!
Notes
You can also boil your sweet potatoes, but roasting them brings out more sweetness.You can adjust measurements if you plan on making a bigger casserole than 9x9 baking dish.