Heat oven to 400 degrees. Pierce sweet potato and butternut squash several times with the times of a fork or knife (this lets steam out while baking). Place the sweet potatoes and butternut squash on a large baking sheet lined with foil. Bake until tender, about 40-45 minutes. Turn oven down to 375 degrees, and spray a large (9×13 inch) casserole dish with cooking spray. Gather ingredients.
Once cooled enough to handle, cut sweet potato and butternut squash in half lengthwise. Remove seed from butternut squash and remove flesh from each.
Place flesh from sweet potato and butternut squash in a blender or food processor with other ingredients and pulse until smooth. Pour into prepared casserole dish.
Meanwhile, to make the topping, mix together pecans, syrup and cinnamon in a small bowl, (and oats if desired). Toss pecans in syrup until well coated. Sprinkle over sweet potatoes.
Bake for 40-45 minutes, or until sweet potatoes are ?set? and/or no longer jiggle in the middle. Serve warm.