In a large mixing bowl, whisk together the flour, brown sugar, granulated sugar, baking powder, baking soda, pumpkin pie spice, cinnamon, and salt until evenly combined. Break up any clumps of brown sugar as you whisk.
In a separate bowl, whisk together the buttermilk, pumpkin puree, eggs, melted and slightly cooled butter, maple extract, and vanilla extract until smooth and well combined.
Pour the wet ingredients into the dry ingredients and gently stir just until no large streaks of flour remain. A few small lumps are fine; avoid overmixing. The batter should be thick but easily scoopable and spread slightly on its own. If it seems too thick, add additional buttermilk 1 tablespoon at a time. Let the batter rest for 5 minutes.
While the batter rests, heat a large nonstick skillet or electric griddle over medium to medium-low heat and lightly grease with butter or oil. Scoop about ¼ cup of batter onto the hot surface for each pancake. Cook for 2-3 minutes, or until bubbles form across the surface, the edges begin to look set, and the underside is golden brown.
Gently flip each pancake and cook for another 1-2 minutes, or until the second side is golden brown and the center is cooked through. Adjust the heat to medium-low as needed if the pancakes are browning faster than the centers can cook.
Transfer the pancakes to a plate and repeat with the remaining batter, lightly greasing the skillet between batches as needed. Serve the pumpkin pancakes warm with butter and pure maple syrup. Enjoy!