Peel and dice the sweet potatoes. Steam or roast them until soft. Mash them until pureed. You can use canned sweet potato puree too.
In a large bowl, whisk together the dry ingredient: flour, baking powder, baking soda, brown sugar, pumpkin pie spice, and pinch of salt.
In a medium bowl, whisk together the buttermilk, eggs, vanilla, and sweet potato puree.
Pour the wet ingredients into the dry and stir just until combined. Do not ovemix.
Heat a skillet or griddle over medium-low heat. Once hot, melt butter or spray with cooking spray and pour abut ½ cup batter onto the skillet.
Cook until the edges of the pancake look slightly brown and bubbles appear on the surface, about 2 minutes. Flip and cook on the other side for an additional 1-2 minutes or until golden brown.