Prick the sweet potato with a fork 4 or 5 times and microwave on high for 15 minutes. Or use your microwaves baked potato setting if it has one, 15 minutes was way too long for my microwave. Hold the potato with a kitchen towel and halve it, scoop out the flesh and transfer to a bowl and mash.
Preheat the griddle over medium-high heat.
In a large bowl, combine the dry ingredients and whisk to combine. In a separate bowl, combine the eggs, milk, buttermilk, and mashed sweet potato and whisk to combine.
Make a well in the center of the dry ingredients, and pour the wet mix into the center of the well. Use a whisk and work from the inside to the out, whisk the wet ingredients into the dry, making a smooth batter.
Melt the butter on the griddle. Use a 1/4 cup measure to pour 1/4 cup of batter onto the griddle for each pancake. Once the pancake begin to bubble, flip them and cook for an additional minute. Transfer cooked pancakes to a plate and keep warm in a low oven while making the rest.