Preheat oven to 400 degrees.
Toss cranberries, sugar, orange juice, melted butter, cornstarch, and mint in a medium bowl.
In a large bowl, whisk together flour, crystalized ginger, baking powder, and salt.
Using a pastry blender or fork, cut cold butter into flour mixture until mixture is crumbly.
Stir buttermilk into mixture, just until dry ingredients are moistened.
Turn dough out onto a lightly floured surface and knead 3 to 4 times.
Pat into a 1-inch thick rectangle and. Cut into 6 squares; cut squares diagonally into 12 triangles.
Lightly grease 6 3.5-inch cast iron skillets and place them on an aluminum foil-lined baking sheet.
Divide cranberry mixture between skillets and place 2 dough triangles over the cranberries in each skillet.
Bake at 400 degrees for 16 to 20 minutes or until cranberries are bubbling and biscuit topping is golden brown.
Cool skillets 15 minutes before serving. Sprinkle additional minced crystalized ginger over the cranberries and serve either warm or at room temperature.