Preheat the oven to 350 degrees and grease a cast iron skillet.
Add the almond flour, buckwheat flour, & vegetable shortening to a bowl.
Use a fork to cut in the shortening into the flour.
Next, add the coconut sugar, salt, egg, and water to the shortening and flour mixture and stir to combine.
Press the crust dough into the cast iron skillet in an even layer and up the sides of the skillet.
Stick the skillet into the oven while you make the filling.
In a separate bowl, add the pumpkin, eggs, soy milk, maple syrup, cashew butter, salt, cinnamon, ginger, and nutmeg.
Use a hand mixer to mix the filling until fluffy and combined.
Remove the skillet from the oven and add the filling to the top of the crust in an even and smooth layer.
Return the skillet to the oven and bake for 45-50 minutes.
Once the pie is cooked through, remove the skillet from the oven and allow it to cool on a flat surface.
Store the leftover, cooled pie in the refrigerator in a sealed container.