Preheat oven to 400 F. Line a baking sheet with parchment paper. In a large mixing bowl whisk together flour, brown sugar, baking powder, baking soda, salt, and cinnamon.
In another bowl, stir together the mashed sweet potato, the buttermilk, and the egg. Pour this liquid mixture over the dry ingredients. Stir until the powders are moistened. Turn the dough over on a lightly floured board and knead briefly just until the dough comes together.
Pat and shape the dough into an 8-inch circle. Cut the circle into 8 wedges. Place the wedges in the baking sheet that is lined with parchment paper, leaving an inch apart in between them. Bake the scones at 400 F for 15-20 minutes, or until the scones are golden.
Stir together powdered sugar, milk, honey and salt until the mixture is smooth. If you prefer a thicker glaze, add more powdered sugar to adjust the consistency.
Recipe for the scones adapted from Taste of Home.