Preheat the oven to 400 degrees.
Sift together the flour, baking powder, sugar, and salt into a large mixing bowl.
Using a pastry cutter, cut the butter into the flour mixture, until it all resembles small peas.
In a small bowl, mix together the yolks, milk, cream, and vanilla. Stir it into the flour mixture just until no streaks of flour are left. Stir in the chocolate chunks.
Dump the mixture onto a floured board, and pat it into a one inch thick circle. Using a floured knife, cut it into 8 wedges. Place them on a parchment lined baking sheet, spaced two inches apart from one another.
Brush each wedge lightly with some heavy cream and sprinkle with the coarse sugar. Bake them for twenty minutes, or until they're light brown.
Make the glaze by combining the sifted powdered sugar with the vanilla and heavy cream. Use a piping bag to apply the glaze to the scones. Serve warm.