Preheat the oven to 325.
To make the dough, add all the dry ingredients to a large bowl and mix well.
Add in the butter, and using a fork or pastry blender, work in the butter to the dry ingredients until the butter has broken down to pea size.
In a small bowl, gently whisk the egg and egg yolk. Add the eggs to the scone batter and mix well. The dough should be holding together at this point.
Add in the fresh blueberries and mix until evenly dispersed.
Line a cookie sheet with parchment paper and sprinkle it with tapioca starch. Pour out the dough onto the cookie sheet, and sprinkle with a bit more tapioca flour on top.
Pat the dough into a circle, about 7-8 inch round. With a very sharp knife, cut a “plus sign” into the dough, creating 4 sections. Now, cut each section into 2 triangles. Think of it as cutting a “plus sign” then an “X” into the dhough. Do not move the individual scones at this point. Since these are grain-free, the dough is too fragile for moving.
Place in the oven and bake for 20 min.
While the scones are baking, add your frozen blueberries to a microwave safe bowl and heat for 30-45 seconds until the blueberries are breaking down and releasing their juices. Muddle and strain the blueberries, collecting the juice in a small bowl.
Add the remaining frosting ingredients to the bowl and whisk until smooth.
The scones are not quite finished baking yet. At this point, remove the scones from the oven, and very carefully take a knife and run it down the cuts you previously made. Gently separate the scones away from one another. Then bake for another 8 minutes.
Allow to cool, then generously frost the scones.
Store in an air-tight container in the refrigerator.