Preheat oven to 425° and lightly spray a baking sheet with non-stick cooking spray. Set aside.
In a medium saucepan over medium high heat, cook 2-3 sweet potatoes until fork tender. Drain water, return to pan and mash.
In a large bowl, whisk dry ingredients together.
Using a pastry cutter or two forks, cut in butter until mixture resembles coarse crumbs.
In a medium bowl, stir mashed sweet potatoes and buttermilk until combined.
Add wet ingredients into dry ingredients and stir until a soft dough forms.
Turn dough out on a lightly flour surface and knead 4 to 5 times or just enough to form a ball.
Roll dough to ½ inch thickness and cut into 2 inch rounds with a biscuit cutter.
Place on prepared baking sheet.
Bake for approximately 15 minutes or until biscuits are lightly browned and puffy.