Make the biscuits: Place the sweet potatoes, milk and melted butter in a large bowl and stir until thoroughly combined.
Set a sifter or fine-mesh sieve over a medium bowl. Resift the 1 1/4 cups flour into the bowl, then sift in the remaining dry ingredients and whisk together. Transfer the dry ingredients to the sweet potato mixture and stir just until a soft dough forms (it’ll be pretty sticky).
Turn the dough onto a lightly floured board and toss until smooth. Roll out the dough 1/2 inch thick, then stamp out as many biscuits as you can (about 15) with a 1- to 1 1/2-inch floured biscuit cutter. Place the biscuits on a parchment-lined baking sheet. Bake until just golden brown, 15 to 20 minutes.
Meanwhile, make the honey butter: Simply whisk together the butter, salt and honey in a small bowl until smooth.
Serve the sweet potato biscuits warm with the honey butter.