Preheat the oven to 350ºF. Grease a 9" pie dish and set it aside.
Start by making the topping. Add all ingredients into a small bowl and mix together. Set aside.
Move onto the apples. If you haven't yet, peel and slice your apples into thin strips (about 1/8" thick). Add the apples into a large mixing bowl. Add the lemon juice, cinnamon, coconut sugar, and arrowroot starch. Mix together and set aside.
And finally, let's make the crust. Add the gluten-free flour, salt, and cold butter into a food processor. Blitz together until the butter is combined with the flour. Add 1/4 cup of cold water and process until combined. Pulse in the next tablespoon of water and then if needed the final one. At this point, the dough should have come together and will be pliable.
Transfer the dough onto a piece of parchment paper. Form into a ball and top with another piece of parchment. Roll out the crust into a circle to about 1/8" thick.
Remove the top piece of parchment paper from the dough and flip it into the pie dish. Press the crust into the dish so that it's even throughout. Fold the top of the crust over slightly and then crimp the edges with your fingertips.
Transfer the apples into the crust and spread evenly throughout. Sprinkle the topping on top.
Bake on the center rack for 50 - 60 minutes until the crust and topping are golden brown and you can hear the apple filling bubbling. Remove from the oven and allow to cool for at least 20 minutes before slicing and serving.
To serve, top with a scoop of vegan vanilla ice cream!