Preheat oven to 425 degrees (F) or 218 degrees (C). Line a baking sheet with parchment paper.
Whisk together until smooth the sour cream, egg, and orange juice. Set aside.
In the bowl of a food processor, pulse together until combined (about 10 pulses) flour, baking powder, baking soda, salt, sugar, and orange zest.
Sprinkle the frozen butter pieces over the top of the flour mixture, then pulse until the mixture resembles coarse meal.
Add the sour cream mixture to the flour mixture and pulse just until the dough comes together. Be careful to not over process the dough.
Turn out onto a lightly floured surface. Sprinkle the chopped chocolate over the dough then gently knead into the mix. Again, be careful to not overwork the dough or it will toughen.
Place the dough onto the parchment-lined baking sheet and pat into an 8-inch circle. Cut into 8 wedges and move them slightly apart.
Bake 12 - 15 minutes. The scones should be golden and the center should look set. Cool scones on a wire cooling rack while preparing the glaze.
Place the chocolate and vegetable shortening into a microwave-safe bowl. Heat on 70% power for 45 seconds. Stir. Heat in additional 20 second increments as needed, stirring after each heat cycle until chocolate is melted and smooth.
Mix in the orange extract and stir until smooth.
Drizzle the chocolate over the scones. Allow to set for 15 minutes then serve.