Preheat oven to 425°F (220°C).

Lightly grease a large baking sheet.

In a large bowl, combine flour, baking powder, salt, baking soda, and 2 tablespoons of sugar.

Using a pastry blender or two knives, cut in the butter until the mixture resembles coarse crumbs.

Mix in the chocolate chips with a fork.

In a separate cup, beat together buttermilk and egg.

Add the buttermilk and egg mixture to the flour mixture.

Mix lightly with a fork until the mixture clings together and forms a ball of soft dough.

Turn the dough onto a lightly floured surface.

Knead gently, turning 5 or 6 times.

With a floured rolling pin, roll the dough into a 1/2-inch thick circle.

Slice the dough into 12 triangular pieces.

Lightly brush the tops of the scones with milk.

Sprinkle the remaining sugar on top of the scones.

Bake the scones for 10 to 12 minutes, or until they are golden brown.