In a large mixing bowl, whisk all dry ingredients together ( flour, sugar, baking powder, soda, salt and nutmeg ).
Add butter and cut it in using a pastry cutter.
Add buttermilk and egg and stir gently until just combined.
Place the dough onto a lightly floured surface, divide into two parts. Flatten each one into a disk, about ½ inch thick.
Cut in half and then each piece in half again and again. You should have 8 scones.
Place them all on a parchment paper-lined baking sheet.
Repeat for the second disk. Now you should have 16 scones nicely placed on a baking sheet. Place the baking sheet into the refrigerator, preferably overnight, or at least 30 minutes.
When ready, preheat the oven to 425 degrees.
Bake the scones for 13 - 15 minutes for the 30-minute refrigerated ones, or 15 - 18 minutes for the overnight refrigerated ones. Cool on wire rack.
to make the butter:
Fluff the softened butter with a fork.
Stir in the jam and orange zest.
Add the powdered sugar and stir all until combined.
Spread over freshly baked scones or refrigerate until you are ready to use it.