Preheat the oven to 375 degrees.
Combine the blueberries with the superfine sugar and set aside.
In a mixing bowl, sift together the flour, baking powder, pinch of sugar, and pinch of salt. With a pastry blender or fork, fold in the butter, mixing until it resembles coarse meal. Add the buttermilk and blend with a fork just until combined.
On a lightly floured surface, pat the dough into a 4-inch square. (It should be about 1/2 inch thick.) Cut 4 biscuits with a 2-inch cutter. Place on a parchment-lined baking sheet, sprinkle with sugar, and top each with 3 almond slivers. Bake for 15 minutes, until golden.
Cut the biscuits in half. Add the yogurt to the blueberries and stir to combine. Place a quarter of the berries on top of one half of each biscuit, and top with the other biscuit halves.