In a bowl whisk together the cassava, arrowroot starch, sugar, sat, baking soda and cream of tartar.
Like you are making a pie, cut the soft butter into the flour mixture until it resembles wet sand. If there are few small pieces of butter still it's okay.
Whisk in the pumpkin puree, eggs, oil, and spices. The batter will be thicker.
Finally whisk in the milk a little bit at a time. Depending on your measurements you might need a little more or less. (½ - 1 C) If I measure by weight I like the results best with ¾ C of milk.
Notes
For best results weight the flours as cassava flour can settle and always spoon measure.Make sure your butter is room temperature but not melted.Use pumpkin puree and not pumpkin pie fillingDepending on your waffle maker this will make 6-8 waffles on average. I prefer the way these get crispy when the waffle maker is fuller so it fills all the cavities.