In a large bowl, place the flour, xanthan gum, baking powder and salt, and whisk to combine well. Add the chopped and chilled butter, and toss to coat it in the dry ingredients.

Flatten each chunk of butter between your thumb and forefinger.

Add 1/3 cup of water and mix until the dough begins to come together. Add the remaining water by the teaspoon until no part of the dough is crumbly.

Turn out the dough onto a lightly floured piece of unbleached parchment paper and press into a disk.

Sprinkle the dough lightly with more flour, and roll it out into a rectangle that is about 1 inch thick, moving the dough frequently and sprinkling it lightly with flour if it begins to stick.

Fold the dough over on itself like you would a business letter. Sprinkle the dough again lightly with flour, and roll out the dough once again into a rectangle about 1 inch thick.

Twice more, remove the top piece of parchment paper, sprinkle lightly with flour, and fold the dough over on itself like you would a business letter.

Wrap the dough tightly in plastic wrap and place in the refrigerator to chill.

Preheat your oven to 425°F. Grease a 9-inch deep dish pie plate and set aside.

Remove the pie dough from the refrigerator.

Place it on a lightly floured piece of unbleached parchment paper, dust lightly with flour, and roll into a 12-inch round, about 3/8-inch thick.

Roll the pie crust loosely on the rolling pin and then unroll it over the prepared pie plate.

Press the pie crust gently into the bottom and up the sides of the pie plate and, with kitchen shears, trim the excess crust so that only 1/4-inch of excess is overhanging the plate.

Tuck the 1/4-inch of excess under itself, and crimp the edge gently all the way around the crust.

Pierce the bottom of the pie crust with the tines of a fork and place the pie plate in the freezer to chill for 5 minutes.

Remove the pie plate from the freezer and place a large piece of unbleached parchment paper in the center of the crust.

Place pie weights or dried beans in a single layer in the center of the pie crust, on top of the paper.

Place in the center of the preheated oven and bake for 10 minutes or until just beginning to brown.

Remove from the oven and remove the paper and pie weights.

Reduce the oven temperature to 325°F.

In a large bowl, place the butter, granulated sugar and light brown sugar, and mix until well-combined.

Add the eggs and vanilla, and mix again to combine.

In a separate, small bowl, place the flour, xanthan gum, baking soda and salt, and whisk to combine well.

Transfer about 1 teaspoon of the dry ingredients to a separate bowl, add the chocolate chips and toss to coat.

Add the remaining dry ingredients to the butter and sugar mixture, and mix until just combined.

Add all but about 1 ounce of the chocolate chips and mix until the chips are evenly distributed throughout the mixture, then scrape the mixture into the parbaked pie shell.

Spread the filling into an even layer, and cover the edges of the crust with foil.

Place the pie in the center of the preheated oven and bake for 30 minutes.

Remove the pie from the oven, remove the foil from the edges and scatter the remaining 1 ounce of chocolate chips on top.

Return the pie to the oven and bake until it’s set in the center and does not jiggle when shaken gently from side to side (about another 15 minutes).

Remove from the oven and allow to cool completely before slicing and serving.