For the gluten-free flour blend: In a large bowl, whisk together the rice flour, tapioca flour, potato starch, xanthan gum and salt.
For the puffs: In a small bowl, whisk the granulated sugar, cinnamon and salt together with 1 cup gluten-free flour blend.
Preheat the oven to 400 degrees F and line a baking sheet with parchment paper. In a medium saucepan over medium heat, melt the butter together with the milk and 1/2 cup water. Increase the heat to medium-high and bring to a boil. Reduce the heat to low and gradually whisk in the flour mixture. Using a wooden spoon, stir the dough until a ball forms, about 3 minutes. Transfer the dough to a food processor and pulse about 20 times to cool. With the motor running, stream in the eggs, egg white and baking powder; process until a smooth dough forms. Using a 1 1/2-inch ice cream scoop, drop the dough onto the prepared baking sheet; bake until puffed and golden, about 25 minutes. Using a sharp knife, cut a slit on the sides of each to vent and let cool completely.
For the filling: Using an electric mixer, beat the cream at high speed until soft peaks start to form. Add the confectioners' sugar, vanilla and spice and beat on medium speed until soft peaks form. Fold in the pumpkin puree. Cut the puffs in half and using an ice cream scoop, place mounds of whipped pumpkin cream on the puff bottoms. Set the tops in place and dust with confectioners' sugar.