Gluten-Free Apple Pie

Ingredients

• 1 cup brown rice flour, 131 grams/4.6 ounces
• 1/2 cup organic cornstarch, 56 grams/2 ounces
• 1/4 cup organic amaranth flour, 34 grams/1.4 ounces
• 1 tablespoon cane sugar
• 1/4 teaspoon xanthan gum
• 1/4 teaspoon salt
• 3 tablespoons ice water
• 1 large egg
• 12 tablespoons cold, cubed butter (6 ounces)
• 2 gluten-free pie crusts for a 9-inch pie plate
• 7 cups peeled Granny Smith apples, sliced 1/4" thick - about 2 1/2 pounds
• 3/4 to 1 cup sugar (if using a tart variety of apple, use more sugar)
• 2 tablespoons gluten-free sweet rice flour or tapioca flour
• 1 teaspoon cinnamon
• 1/8 teaspoon nutmeg
• 2 tablespoons cubed butter