Preheat oven to 400 ℉

Peel and cut the sweet potato into chunks and put on to boil, just until soft, roughly 15 minutes.

While boiling potatoes combine flour, baking powder, salt in a medium bowl and whisk together to mix. Set aside. 

If making in 8x8 dish you can put the butter in dish and place in the oven to melt. If using biscuit pan slice and divide the butter into 9 pats, one for each biscuit. Melt butter in oven and set aside. 

Drain potatoes and mix in brown sugar and sugar using a hand mixer or potato masher, turning it into a puree.

Add the sweet potato mixture into the dry ingredients. Using a fork mix together to start to form a dough.

Gradually add milk until a sticky dough is formed. You may not need all the milk. 

Using a spoon or ice cream scooper spoon and drop the dough into the pan. 

Place in oven and bake for ten minutes or so. Open and using a basting brush, brush the tops with the surrounding butter and continue to bake additional 7-10 minutes until golden brown. 

Remove from oven and allow to cool.