Preheat oven to 425.
Pierce the sweet potato all over. Microwave on high until soft, about 3 to 5 minutes. Remove from oven and allow to cool enough to work with. Remove and discard skin, add sweet potato to a bowl (should be about 3/4 cup of sweet potato mash).
Add the beer to the sweet potatoes and using a potato masher, stir and mash until completely combined.
In a bowl, add the flour, baking powder, baking soda, salt and sugar. Mix to combine.
Add the butter cubes and using your fingers or a pastry blender, rub the butter into the flour until completely combined.
Add the sweet potato beer mixture and mix until just combined.
Form dough into a ball and place on a lightly floured surface. Form into a square, about 1 1/2 inches high, and about 1 foot long. Cut into square biscuits. Place on a baking sheet covered with a Silpat or parchment paper. Brush with melted butter.
Bake at 425 for 15-18 minutes.
In a small bowl, add the maple syrup ingredients and stir until combined.
Serve biscuits warm, with maple sage butter.