Grease and flour two 9x5-in. loaf pans. Line bottoms of pans with waxed paper and grease the paper; set aside.
In a large bowl, combine the first 11 ingredients. In another large bowl, whisk the eggs, sweet potatoes, oil, water and extract. Stir into dry ingredients just until moistened; fold in pecans.
Transfer to prepared pans. Bake at 350° for 60-70 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before removing from pans to wire racks. Carefully peel off waxed paper.
For topping, in a small saucepan, combine the brown sugar, corn syrup, butter and vanilla. Cook and stir over medium heat until butter is melted. Remove from the heat; stir in pecans. Pour over loaves. Cool completely before cutting.