In a large bowl, whisk together flour, baking powder, baking soda, brown sugar, salt, cinnamon, nutmeg, and ginger.
In a separate bowl, whisk together buttermilk and sweet potato puree, then add eggs and vanilla.
Add wet ingredients to dry ingredients and stir with a wooden spoon until just combined.
Melt butter in a large nonstick skillet or griddle over medium heat. When butter is foamy, reduce heat to medium-low and ladle a scant ½ cup pancake batter into skillet. Cook until bubbles start to form in batter and pancake is golden underneath, about 3 minutes, then flip and cook other side until golden, another 3 minutes.
Repeat with remaining batter. Serve with more butter, toasted pecans, and maple syrup.