Peel sweet potato(es) and cut into small cubes. Place in small saucepan filled with cold water. Bring to boil and then simmer for 10 minutes or until soft.
Drain sweet potatoes and mash with 2 tablespoons butter. Allow them to cool away from the heat for 20-30 minutes. *See Note.
Preheat oven to 450 degrees and prepare a baking sheet by lining it with parchment.
In a large bowl, whisk together 1 1/4 cup flour, 3 tablespoons brown sugar, 1 tablespoon baking powder, 1 tablespoon fresh sage, 1/2 teaspoon baking soda, and 1/2 teaspoon salt. With a pastry cutter, cut in 6 tablespoons butter and mix until it is a coarse mixture.
Add the completely cooled mashed sweet potatoes, and two tablespoons milk.
Mix dough by hand until combined. If you find that the dough is too dry, add more milk only 1 teaspoon at a time.
Place dough onto a lightly floured surface. I like to use a piece of parchment dusted with flour. Using a rolling pin, gently roll out to 1" thickness. Use a 2 1/2 inch biscuit cutter to cut the biscuits.
Place biscuits onto the prepared baking sheet. Bake for 13-15 minutes until a toothpick inserted into the center comes out clean.
These are extra delicious slathered with butter and drizzled with some honey!