In a mixing bowl, add the flour, sugars, baking powder, and salt. Stir to combine.
Add the cold, cubed butter. Using a pastry cutter, cut the butter into the flour mixture until the mixture resembles coarse crumbs with bits of butter about the size of small peas. Toss in the chopped chocolate.
Next, in a small pitcher or bowl, mix together the cream, vanilla, and egg. Then, pour the cream mixture into the flour and butter and gently stir to combine.
On a board lightly dusted with flour, shape the dough into a circle (about 8 inches). Cut into 6 large wedges or 8 smaller wedges. Transfer to a parchment-lined baking sheet. Brush the tops with extra cream.
Bake for 15-20 minutes lightly brown around the edges and a cake tester inserted in the center of a scone comes out clean. Let cool.
Meanwhile, add the powdered sugar and heavy cream to a small bowl. Whisk to combine. Add more cream as needed to achieve a drizzling consistency. Drizzle the glaze over the scones. Enjoy!