Combine Gluten-Free All-Purpose Flour (2 cup), Xanthan Gum (3/4 teaspoon), Baking Powder (1/4 teaspoon) and Salt (1/2 teaspoon) in a large mixing bowl.
Grate the Butter (6 tablespoon) onto a plate and then empty into your dry ingredients.
Work the butter in between fingers pressing it into the flour mixture to form a shaggy dough.
Add Sour Cream (1/2 cup) and stir until the dough starts to clump, then knead the dough on a floured work surface until it holds together. Keep additional Water (1/4 cup) on hand in case you need more to loosen the dough. Form the dough into a disk and chill for 30 minutes.
Preheat oven to 375 degrees F (190 degrees C).
Divide the dough in half. Using a floured rolling pin and a floured work surface, roll out the dough until it reaches 1/2-inch all around. Shape into the pie or tart pan and chill in the fridge for another 30 minutes.
Using a fork, poke holes in the bottom of your crust. Careful not to pierce all the way through the dough. Prebake the crust for 10 minutes with pie weights before using as desired.