In a large bowl, whisk together flour, sugar, baking powder and salt. Add the butter and use a pastry blender to cut butter into flour mixture until you have a coarse meal.
Stir in one egg (beaten), sourdough discard, orange zest, cranberries and milk.
Turn out onto a floured surface and need gently about 10 times. Pat down to 1/2 inch thick circle. Cut into 8 slices and place on an ungreased or parchment lined baking sheet. Brush triangles with second (optional) egg if using with a pastry brush.
Bake for about 15-18 minutes, until lightly golden.
Icing
Whisk together orange juice, powdered sugar and orange zest in a small bowl until smooth. Pour into a ziploc bag and snip a 1/4 inch off the corner of the bag when ready to glaze the scones (make sure they are cool).
Drizzle the icing over each scone in a zigzag pattern.