In a large bowl, whisk together the flour, brown sugar, baking powder, baking soda, salt and pumpkin pie spice.
In a separate bowl, whisk the pumpkin puree, buttermilk, melted butter and vanilla until smooth.
Pour the wet ingredients into the dry ingredients and stir gently until no dry streaks remain. Let the batter rest for 10 minutes so it can thicken and puff up.The pumpkin works as a natural binder here, so the pancakes hold together beautifully without eggs.
Stir the softened butter, maple syrup and cinnamon together in a small bowl until smooth.
Heat a griddle or large nonstick skillet over medium-low heat and grease it lightly. Pour 1/4 cup of batter per pancake, spread it slightly and cook for 2-3 minutes, until bubbles form and the edges look set.Flip and cook for 1-2 minutes more, until golden and cooked through. Pumpkin batter browns quickly, so keep the heat on the gentle side.
Stack the warm pancakes and top with a spoonful of maple butter, a drizzle of maple syrup and a sprinkle of toasted pecans.