Heat oven to 400 degrees and move rack to the upper middle position.
In a mixing bowl, mix flour, baking powder, baking soda and salt. Then grate the frozen butter into the flour mixture on the large holes of a box grater. Work the butter into the flour until it becomes like coarse meal. You can also do this step in the food processor. (But that means you have to wash your food processor and who needs that!?)
In a second bowl, whisk Greek yogurt, 1/3 cup maple syrup, egg, vanilla, and the zest from a lime until the mixture is uniform and smooth.
Using a fork, stir the Greek yogurt mixture into flour mixture until large dough clumps form and there is no loose flour in the bowl. Add the cup of berries and mix the berries gently into the dough until they are evenly distributed. (You want to work with the blueberries as gently and as little as you can because they will turn the dough blue.) Then use your hands to press the dough into a ball. (There may not seem to be enough moisture at first, but as you work the dough it will come together.)
Turn out the dough onto a lightly floured surface or parchment paper and pat it into an 8-inch circle about 3/4-inch thick. Use a sharp knife to cut into 8 triangles. Place the triangles on a cookie sheet lined with parchment paper about an inch apart. Bake until golden, about 16 to 18 minutes.
While the scones are baking, whisk softened cream cheese, maple syrup and the juice from your lime until smooth. I store it in a jar and drizzle it across my scones right before serving. Or put it on the table and let everyone serve themselves. Just pop the lid back on the jar and store any extra sauce in the fridge.