In a large mixing bowl, mix the flour, sugar, baking powder, baking soda, and salt. Cut in the butter with a pastry blender (or two knives) until it resembles coarse oatmeal.
Add the buttermilk all at once and mix a few strokes. Add the nuts and dried fruit, and mix just until the dough comes together.
Turn the dough out onto a floured surface and split in two. Using well-floured hands, pat and shape (but do not knead) the dough into two round disks, approximately 1.5″ thick. By the time you have the disks shaped, you’ll have used about 600 grams of flour – you want the outside to no longer be sticky. The inside of the dough will still seem wet, but holding its shape.
Transfer the disks to a parchment covered baking sheet and freeze for 30 minutes.
Preheat the over to 425F. Remove the disks from the freezer, cut into six equal portions (one cut down the middle and cut each half into thirds). Separate them on the baking tray by a few inches (to allow room for rise).
Bake 20-28 minutes, until puffed up and golden brown.