Preheat oven to 425 degrees adn butter a round cake pan. (Or use parchment paper)

Whisk flour, sugar, baking powder, baking soda and salt together in a large bowl.

Use a pastry blender (or 2 forks) to cut in cold butter until it resembles cornmeal.

In a separate bowl, mix sweet potato puree and buttermilk together until smooth.

Stir sweet potato mixture into flour mixture until just combined into dough.

Lightly flour a surface and turn dough onto it.

Knead the dough 5-6 times gently, until dough comes together.

Shape dough into a round shape about 1" thick.

Using a biscuit cutter of desired size, cut out biscuits.

Arrange biscuits in the prepared pan.

Brush the tops of biscuits with melted butter.

Bake 20-24 minutes or until golden.