Add flour, baking powder, salt, cinnamon, ginger powder, and grated nutmeg in a medium mixing bowl. Lightly mix until everything is evenly incorporated.
Add sweet potato puree, brown sugar, buttermilk, eggs, and vanilla in a larger mixing bowl. Using a hand mixer, mix until fully combined, 2-3 minutes.
Pour the dry ingredients into the wet ingredients and continue mixing until combined. Don't overmix, but you want the flour to be completely moistened.
Finally, add 2 ounces of melted butter (save the rest to cook the pancakes) and fold in using a spatula. Set batter aside.
Preheat a large nonstick cast iron skillet over medium heat and lightly grease with melted butter. Once the pan is heated, use ¼ cup scoop of pancake batter and pour on the heated skillet. Cook until bubbles form and the edges dry (2-3 minutes).
Flip the pancakes and cook for an additional 1-2 minutes before removing them from the skillet. Remember, do not be tempted to push down on the pancakes as they finish cooking. Repeat the process with the rest of the pancake batter.
To keep the pancakes warm until ready to serve, preheat the oven to 200℉/95℃. Once heated, place a baking sheet fitted with a cooling rack into the oven, then transfer the pancakes to the baking sheet.
Serve sweet potato pancakes with butter, maple syrup, and nuts as desired.