Preheat oven to 425 degrees.
In a large bowl, mix together flour, baking powder, brown sugar, cinnamon and salt until combined.
In a separate, smaller bowl, combine mashed sweet potatoes, shortening, egg and milk. Stir well until shortening is incorporated.
Add sweet potato mixture to flour mixture, stirring to form a dough.
Place dough on a lightly floured surface and roll to about 1/4 to 1/3 of an inch thick.
Using a biscuit cutter or the rim of a drinking glass cut dough into rounds and place on a cookie sheet.
Bake for 10 to 12 minutes, until lightly browned.