Step 1

Mix the dry ingredients: Combine the millet flour, tapioca starch, granulated sugar, xanthan gum, and salt in the bowl of a food processor fitted with the blade attachment. Pulse a few times to combine.

Step 2

Cut in the fat: Add the butter or fat pieces. Pulse in short bursts (about 3 seconds each) until no large pieces of butter remain. The mixture should look coarse, with pieces of fat no larger than a pea.

Step 3

Add the water by hand: Transfer the mixture into a large bowl. Add 6 tablespoons of the water. Stir with a wooden spoon until it just holds together. If the dough seems dry, add additional water 1 tablespoon at a time.

Step 4

Mix the dry ingredients: Whisk the millet flour, tapioca starch, granulated sugar, xanthan gum, and salt together in a large bowl.

Step 5

Cut in the fat: Cut in the fat with a pastry cutter until no large pieces of butter remain. The mixture should look coarse, with pieces of butter no larger than a pea.

Step 6

Add the water by hand: Add 6 tablespoons of the water. Stir with a wooden spoon until it just holds together. If the dough seems dry, add additional water 1 tablespoon at a time.

Step 7

Chill the dough: Dust a work surface with white rice flour. Divide the dough in half and pat each half into a disk. Wrap each disk well with plastic wrap and chill for 2 hours.

Step 8

Bring the crust to room temperature: Remove the pie dough from the refrigerator and allow to sit out for about 10 minutes before rolling.

Step 9

Sandwich the dough between parchment paper: Place a 13x18-inch piece of parchment paper on a work surface and lightly dust with white rice flour. Place a piece of dough on the center of the parchment and sprinkle with a little more flour. Cover the dough with the second piece of parchment paper.

Step 10

Roll out the dough: Roll the dough from the center to edges, rotating the dough about a quarter of a turn after each roll. This keeps the dough round. Roll the crust about 2 inches larger than the bottom diameter of your pan. (For a 9-inch pie pan, roll the out into an 11-inch circle. This allows for enough dough to cover the sides of the pan.)

Step 11

Line the pie plate: Remove the top piece of parchment from the dough. Invert the pie plate onto the center of the dough. Slide your hand between the bottom sheet of parchment paper and your counter. Place your other hand firmly on the back of the pie plate. In one swift motion, flip the dough and plate. Gently press the dough into the edges of the plate and then slowly pull off the top piece of parchment.

Step 12

Repair and trim the dough: Repair any cracks. If any part of the dough cracked or ripped, gently press it back together. Trim the edges of the crust. Crimp the edges with a fork if desired. (This is for a single-crust pie. For a double-crust pie, see Recipe Notes below.)

Step 13

Chill the crust: Chill the crust for 15 minutes before baking.