Preheat the oven to 200°F. Place a wire rack on a large baking sheet and set aside.
In a medium bowl, whisk together the gluten-free flour, dark brown sugar, baking powder, salt and pumpkin pie spice.
In the bowl of a stand mixer, or using a hand mixer, beat the eggs (do not separate) for 1-2 minutes until light and fluffy. Add the milk, pumpkin, melted butter, maple syrup and vanilla extract and beat on medium speed until combined.
Add the dry ingredients and beat until just combined.
Preheat the waffle iron. When the waffle iron is hot, lightly spray the inside with cooking spray, then scoop in the batter. Cook according to the waffle maker’s instructions.
Serve immediately or keep warm on the wire rack-lined baking sheet in the warm oven until ready to serve.