Preheat the oven to 400 degrees, and cover a baking sheet with parchment paper.
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 resembles small peas.
In a small bowl, mix together the yolks, milk, cream, vanilla, and lemon zest. Stir it into the flour mixture, just until no streaks of flour are left.
Dump the mixture on to a floured board. Add the berries to the dough, and pat it all into a circle about one inch thick. Using a floured knife, cut the circle into eight wedges. Place them on a baking sheet, spaced two inches apart.
Brush each wedge lightly with some heavy cream and sprinkle with coarse sugar. Bake them for twenty minutes, or until they're light brown.
Make the glaze by combining all the ingredients. Use a piping bag to apply to the glaze to the scones. Serve warm.