Combine all the flours and xanthan gum in your food processor, or whisk in a large bowl.
Pulse or cut in the chilled butter until it is pea sized, and slowly add the water until you can pinch it together and feels plyable.
Roll the dough into a ball, cover with plastic wrap, and let the dough chill in the refrigerator for an hour or 2.
Meanwhile, you can make the cherry filling. Combine the cherries and sugar in a sauce pan and start to bring to a boil, while you add the lemon juice and vanilla.
Simmer about 5 minutes and add the cornstarch while stirring until it is all combined. Simmer on low about 10 minutes and take off the heat.
When your dough has chilled, take it out, knead it for a minute to make it plyable to your warm hands, divide it in half (one for the bottom and one for the top of the pie), and then roll out the bottom pie crust on a floured surface (I use rice flour).
Put the rolled out crust in the bottom of your pie plate, crimp the sides, and use a fork to poke holes in the bottom of the crust.
Pour the cherry filling into the pie crust.
Roll out the second ball of dough and either cover completely, or make a lattice top.
Brush the top crust with butter and sprinkle pure cane sugar.
Bake the pie on a cookie sheet at 425 degrees for 15 minutes, then reduce the heat to 350 degrees for 25 min. Let cool for an hour.