How to Make It
Preheat oven to 400°.
Combine the first 6 ingredients in a bowl; cut in margarine with a pastry blender or 2 knives until the mixture resembles coarse meal. Add buttermilk and egg, stirring just until moist (dough will be sticky).
Turn dough out onto a lightly floured surface; with floured hands, knead lightly 4 times. Pat dough into a 10-inch circle on a baking sheet coated with cooking spray. Cut dough into 10 wedges, cutting into, but not through, dough. Bake at 400° for 15 minutes or until golden.
Combine hot water and coffee granules in a medium bowl; stir well. Add powdered sugar; stir well. Drizzle over scones. Cut into 10 wedges; top each with 1 walnut half.