Preheat oven to 375°F. Mix flour, sugar, baking powder, cinnamon, baking soda and salt in large bowl. Cut in butter with pastry blender or 2 knives until mixture resembles coarse crumbs.
Beat eggs, sour cream and vanilla in medium bowl with wire whisk until well blended. Add to flour mixture; stir until a soft dough forms. Stir in chopped chocolate.
Place dough on lightly floured surface. Knead about 1 minute or until smooth. Place dough on greased baking sheet. Pat into a 10-inch circle. Score top of dough with sharp knife into 12 wedges.
Bake 30 minutes or until golden brown. Cool slightly on wire rack. Melt and drizzle additional semi-sweet chocolate over scones, if desired. Cut into 12 wedges to serve.