Preheat oven to 375° F. Mix flour, brown sugar, cocoa powder, baking soda, baking powder and salt in a large bowl. Cut in VERY COLD butter, using a hand held pastry blender or two forks. Cut the butter into dry ingredients until butter is reduced to the size of peas.
Add yogurt and egg yolk to the bowl. Mix by hand, or with electric beater until fully blended. The dough is fairly thick, so if mixing by hand, it will take a few minutes to bind together. Add white chocolate chips to dough, and stir to combine. Place dough on lightly floured work surface. Knead dough with the palms of your hand 10 times, folding dough over, after each time. Do this until the dough comes together in a ball.
Pat and shape dough with your hands until it is formed into a 9" wide circle. Use a sharp knife or a pizza cutter to evenly cut dough into 8 pie shaped wedges. Put scones on an ungreased baking sheet, about 1" apart, so they stay separated while baking. Bake at 375° F. for 17-18 minutes.
When done, remove pan from oven, and let scones cool for 5-10 minutes, still on the pan. Place a piece of wax paper on the counter, with wire rack on top. Transfer scones to the wire rack. TIP: The wax paper will collect any drips when you drizzle the scones with glaze, making cleanup much easier!
Make The Glaze: While scones cool, mix together powdered sugar and a few drops of water at a time, in a small bowl. Stir. Add a couple more drops of water, and stir. Continue to do this until the glaze is an easy to drizzle consistency... not too thick, and not too thin! Too thick? Add drops of water. Too thin? Add powdered sugar! Drizzle the glaze over the tops of the cooled scones, using a spoon or fork. Let glaze firm up, then scones are ready to serve. Enjoy!
Double Chocolate Scones https://www.thegratefulgirlcooks.com/double-chocolate-scones/