In a mixing bowl, combine flour, sugar, baking powder, soda, and salt.
Cut in butter. Stir in chocolate. Mix egg and milk; add to dry mixture. Stir till just moistened. Form into a ball.
Turn dough out onto a floured surface. Knead for 12 to 15 strokes or till nearly smooth. Pat or lightly roll to 3/4-inch thickness. Cut with a 2-1/2- to 3-inch cutter or cut into squares. Place 1 inch apart on a greased or parchment-lined baking sheet.
Bake the scones in a 375 degree F oven 15 to 18 minutes or until golden. Remove; cool on a wire rack for 5 minutes.
Mix together the icing. Drizzle over scones. Serve warm. Makes 12 servings.
In mixing bowl, mix powdered sugar and vanilla. Stir in 1 tablespoon milk. Add more milk, 1 teaspoon at a time, until it's a drizzling consistency.