Preheat oven to 450°F.
In a large bowl, whisk together flour, baking powder, salt, granulated sugar, cinnamon, and nutmeg. Set aside.
In a separate bowl, combine mashed sweet potato, brown sugar, milk, and vanilla extract. Whisk until smooth. Remove and discard any stringy pieces caught on the whisk.
Microwave 1 stick of butter until it has melted. Pour melted butter into a 9x9 inch baking dish.
Make a well in the dry ingredients, then pour in the sweet potato mixture. Stir gently until just combined and no patches of dry ingredients remain. Be careful not to overmix. Small lumps in the batter are ok.
Pour batter into the pan over the melted butter. Use a spoon or spatula to gently spread batter evenly into the corners. Do not stir the batter into the butter.
Use a knife to carefully cut the dough into 9 squares.
Place the baking dish on top of a foil-lined cookie sheet to catch any spillover. Bake for 20–30 minutes, or just until biscuits are golden brown and a toothpick inserted in the center comes out clean.
Mix together melted butter and honey to create glaze. Brush glaze over hot biscuits. Let biscuits rest at least 5 minutes before serving. Enjoy!