I just tried Baking Powder Biscuits using this formula. Success! They didn't brown very well, but they had a good biscuit texture, didn't taste at all "grainy/dusty" and were delicious with the hamburger soup I made for supper.
1 1/3 cups Gluten Free flour blend
4 tsp baking powder
1/2 tsp salt
1/2 tsp xanthan gum
1 cup almond milk
1/4 cup Canola oil*
Measure flour blend, baking powder, salt and xanthan gum into a medium sized bowl. Whisk together until well blended. Add milk and oil. Beat with a whisk or rubber tipped spatula until very smooth and dry ingredients are well incorporated. Batter will seem too runny, but let it stand for 30 minutes, and the flours will absorb the liquid, making it thicker. Set the oven to 350* F. After a 30 minute rest, drop batter onto a parchment lined baking sheet into 9 mounds. Smooth and shape the batter mounds (with a spoon or fingers dipped in cold water) and bake for 20-30 minutes, until the tops are firm and slightly browned. The biscuits didn't get as golden brown as traditional/wheat flour biscuits, but they had a good texture and tasted quite delicious.
To turn these into "scones", add 1/4-1/3 cup sugar to the dry ingredients, brush the tops of the biscuit rounds with almond milk and sprinkle with sugar. The dough can also be formed into one large round, brushed with almond milk, sprinkled with sugar and scored with a knife into 6-8 pie shaped wedges to create more traditional scones.
*I've also used Becel Vegan Margarine with good results. Biscuits were pretty much the same with the vegan margarine as they were with the oil, so I've been using oil as it's less expensive than the margarine, choosing to save the margarine for eating on the biscuits.