Preheat oven to 400F. Line a baking sheet with parchment paper and set aside.
In a food processor, combine gluten-free flour blend, xanthan gum (if using), baking powder, baking soda, salt, ground black pepper and garlic powder. Process until combined.
Then, add the cold butter to the food processor and pulse 10-15 times, until the mixture is crumbly and the butter cubes have become the size of small peas.
Then, transfer the flour and butter mixture to a large bowl.
Stir in the bacon, green onions and 1 1/4 cups of the shredded cheddar cheese.
Then, stir in 1 cup of the buttermilk. Gradually add the remaining 1/4 cup until a dough forms.
Transfer the dough to a floured surface. Shape the dough into an 8-inch disk.
Slice into 8 wedges. Place the scone wedges on the prepared baking sheet.
Brush the tops of the scones with additional buttermilk. Sprinkle with remaining 1/4 cup of shredded cheddar cheese.
Bake at 400F for 18-20 minutes until the scones are golden brown. Let cool for a few minutes before serving.