Recipe: Sweet Potato and Green Onion Biscuits

-2 cups flour

-4 tsp baking powder

-1 Tbs sugar

-1 tsp salt

-4 Tbs fresh green onion, thinly sliced

-½ cup cold butter, cut into small pieces

-1 egg

-½ cup buttermilk

-½ cup sweet potato puree

-1 Tbs milk for brushing the tops of the biscuits