Preheat oven to 375°F. Scrub sweet potatoes. Pierce each several times with a fork and wrap tightly in foil. Place on a sheet pan. Bake 90 minutes or until tender. Set aside until cool enough to handle. Meanwhile, place oats in a food processor; process 1 minute. Add 4 oz butter, brown sugar and pecans; pulse five times to combine. Spread mixture on a baking sheet; bake 10 minutes. Remove from oven, crumble. Bake 5 minutes or until golden brown. Melt remaining 8 oz butter. Remove skin from cooled sweet potatoes. In a large bowl, whisk sweet potatoes, melted butter, granulated sugar and remaining ingredients until slightly lumpy. Transfer to a greased baking dish, smoothing surface evenly. Top with oat mixture. Bake 12 minutes or until heated through.