In a large mixing bowl, combine the gluten-free flour blend, xanthan gum (if needed), sugar, and salt.

Add the cubed cold unsalted butter into the flour mixture. Use a pastry cutter or your fingertips to work the butter into the flour until it resembles coarse crumbs.

Gradually pour in the cold water while stirring with a fork until the dough starts coming together.

Turn the mixture onto a lightly floured surface and gently knead until smooth.

Flatten the dough into a rectangle, wrap tightly in plastic wrap, and refrigerate for at least 30 minutes.

After chilling, remove from the refrigerator and roll out on a floured surface into a large rectangle (about ¼ inch thick).

Arrange thin slices of cold, unsalted butter over two-thirds of the rolled-out dough.

Fold the unbuttered third over the middle third, then fold over the remaining third on top.

Rotate the dough 90 degrees and roll it out again into another rectangle; repeat the folding process.

Roll out one last time before wrapping tightly in plastic wrap and refrigerating for another 30 minutes.