Preheat the oven to 350 degrees. Line a baking sheet with parchment paper and then set side.
In a large bowl, sift together the flour, baking powder, sugar and salt (a wire whisk is great for this). Using a pastry cutter or two knives, cut the 1/4 cup of cold butter into the flour mixture until it looks like coarse crumbs. Fold in the white chocolate chips and blueberries.
In a small bowl, whisk together the eggs and buttermilk until well-combined. Make a well in the center of the dry ingredients and pour in the egg mixture. Stir gently from the inside out until the dry ingredients are all moistened. The dough will be crumbly.
Turn out the dough onto a floured board and with floured hands, pat into a 3/4-inch thick circle. Using a pizza wheel, cut into eight triangles. Carefully move from the cutting board to the prepared baking sheet. I use an offset spatula, which is perfect for it.
Melt the remaining tablespoon of butter and brush the tops of the scones with it. Sprinkle with coarse sugar.
Bake for 18-20 minutes, until cooked through and just starting to turn golden at the peaks.
Enjoy hot from the oven or let cool and store in an airtight container at room temperate for up to two days.