Preheat oven to 400 degrees. Using mixer with paddle attachment, combine the flour, baking powder, salt, and black pepper in large bowl on low speed. With mixer running, gradually add the butter until the mixture is crumbly and the bits are about the size of peas. Add grated cheese and mix just until well blended. Add the green onions, bacon and ¾ cup of buttermilk to the flour and cheese mixture. Mix by hand until all ingredients are incorporated. If the dry is too dry to hold together, use the remaining buttermilk, adding 1 T. at a time, until the dough is pliable and can be formed into a call. Stir as little as possible to keep the scones as light as possible. Place dough on a lightly floured flat surface. Pat the dough into a ball. Using a well-floured rolling pin, flatten the dough into a circle about 8 inches wide and ½ inch thick. Cut the dough into 8 to 10 equal wedges, depending on the size of the scone you want. Whisk the egg and water in a small mixing bowl to combine. Brush each wedge with the egg wash. Place the scones on an ungreased baking sheet and bake for 18 to 20 minutes or until golden brown and no longer sticky in the middle. Serve warm.