Add flour mixture and pecans to the sweet potato mixture. Combine flour, cinnamon, baking soda, baking powder, and salt in a second bowl. The tops were big and puffy, and the outside (after being coated with butter and sugar and more sugar) were the perfect amount of sturdy and crunchy. These muffins were so unique! You optionally can add 1/2 cup of toffee bits (Bits 'O Brickle Bits) to the muffins or turn them into a bread. Combine sugar, sweet potato, olive oil, water, and eggs in a bowl. These sweet potato muffins get extra texture and flavor from pecans and the cinnamon-sugar topping. The sweet potato purée lowers the amount of oil needed in the recipe and makes the muffins very moist. Ironically, these sweet potato muffins are actually good for your eyes (cue weak segway).