Preheat oven to 400. Combine flour, sugar, baking powder, baking soda and salt in a mixing bowl. Whisk briefly to blend. Add butter to dry ingredients using a pastry cutter or 2 knifes until mixture resembles coarse meal and largest butter pieces are the size of peas. Stir in egg, vanilla, and buttermilk and mix gently with fork until dough forms. Knead briefly, about 10-15 times, until dough has come together. Do not over handle, dough can get tough and dense.
Line baking sheet with parchment paper. Turn dough out onto well floured surface. Roll dough out into a 10x12 inch rectangle. Brush half dough lightly with buttermilk. Lay peaches in a single layer over buttermilk side of dough and sprinkle about half of cinnamon sugar mixture over peaches. Carefully fold over other side of dough over peaches as if closing a book and push down gently. slice dough into 8-10 equal size pieces. Transfer to prepared baking sheet. Brush top of each scone with buttermilk and cinnamon-sugar.
Bake, rotating pan halfway through baking, until tops are golden brown and scones are baked trough about 15-18 minutes. Let cool about 2-3 minutes on baking sheet and then gently transfer to wire rack. Serve warm.