In a large bowl, whisk together the gluten-free flour, xanthan gum (if using), baking powder, baking soda, garlic powder, and salt until well combined.

Cut in the 6 tablespoons of cold butter using a pastry cutter or two knives until the mixture resembles coarse crumbs.

Stir in the 1 cup of shredded cheddar cheese. Create a well in the center of the mixture.

Pour the 1 cup of buttermilk and 1 large egg into the well and gently stir just to combine, being careful not to overmix. The dough will be thick and sticky.

Lightly flour a piece of parchment paper and place the dough on top, then lightly dust the dough with additional flour.

Flatten the dough into a rectangle about 1 inch thick using your fingers.

Gently fold the dough in half, adding just enough flour to make the dough manageable if necessary.

Fold the dough in half again to create layers.