Preheat oven to 400 degrees. Line a baking sheet with a silpat liner or parchment paper and set aside.
Add cranberries to the bowl of a food processor fitted with the standard blade. Pulse until cranberries are chopped into small bits. Alternatively, chop cranberries with a chef's knife. Transfer chopped berries to a small bowl and set aside.
In the same food processor bowl, pulse flour, salt, baking powder, sugar and orange zest until well combined, about 5-6 pulses. Sprinkle cold, sliced butter over top and pulse again until the mixture resemble coarse meal. Alternatively, combine flour, salt, baking powder, sugar and orange zest in large bowl. Cut in cold butter with two forks or pastry cutter, or rub together with fingertips until mixture resembles coarse meal. Transfer flour mixture to a large bowl.
In a small bowl, whisk together the egg, mascarpone cheese, and cream. Add to flour mixture and mix with wooden spoon until mixture begins to come together. Add in the chopped cranberries and chocolate chips (if using) and mix until combined into a rough, shaggy dough.
Pour the dough onto a lightly floured work surface and gently knead until mixture comes together. Pat into a roughly 8" circle and cut into eight wedges with a sharp knife or a bench scraper.
Places the cut scones on the baking sheet. Combine the remaining egg with a teaspoon of milk and brush over scones.
Bake for 18-20 minutes, or until the tops are lightly golden brown. Set aside to cool for 5-6 minutes before glazing.
While scones are baking, combine orange juice, remaining orange zest, salt and powdered sugar to make a glaze. Drizzle over slightly-cooled scones and serve.