Preheat the Oven: Preheat your oven to 425°F (220°C) to ensure it is hot enough for baking.
Prepare the Sweet Potato: If not already done, peel and boil the sweet potato until tender. Mash it well and let it cool.
Mix Dry Ingredients: In a large mixing bowl, combine the all-purpose flour, baking powder, salt, and granulated sugar. Use a whisk to ensure everything is evenly mixed.
Add Butter: Add the cold, cubed unsalted butter to the dry ingredients. Using a pastry cutter or your fingertips, work the butter into the flour until the mixture resembles coarse crumbs.
Incorporate Wet Ingredients: In a separate bowl, mix the mashed sweet potato, milk, and vanilla extract until well combined. Pour this mixture into the dry ingredients.
Combine Ingredients: Stir gently until the dough comes together. Be careful not to overmix; a few flour streaks are acceptable.
Shape the Biscuits: Turn the dough out onto a floured surface. Pat it into a 1-inch thick rectangle. Use a biscuit cutter or a glass to cut out the biscuits and place them on a parchment-lined baking sheet.
Bake: Bake the biscuits in the preheated oven for 15-20 minutes, or until they are golden brown on top.
Cool and Serve: Allow the biscuits to cool slightly before serving. Enjoy them warm, preferably with butter or your choice of topping.