Preheat the oven to 400 degrees Fahrenheit.
Whisk together all dry ingredients in a large bowl aside from the berries.
Cut the frozen butter into cubes and cut into the dry ingredients using a fork or pastry cutter until it is well mixed in. The mixture should just look very crumbly at this point.
It's ok if you have a few visible pieces of butter, but you don't want any chunks.
In a small bowl, whisk together all remaining wet ingredients. Be sure to shake up the can of coconut milk really well. If you open it and it seems lumpy, just give it a whisk or blend it until smooth.
Pour the wet ingredients into the dry and mix well until a dough forms. It will be sticky.
Fold in the blueberries.
Transfer to a floured surface and mold into a round disc.
Cut in half, then in half again, then cut each quarter in half. You should end up with 8 triangles.
Place on a baking sheet lined with parchment paper, spacing each at least an inch apart. Sprinkle the tops with sugar.
Bake for 18-25 minutes or until just lightly golden brown.
Serve as is, or whisk together 1 cup of powdered sugar with a few teaspoons of milk or lemon juice and drizzle on top.