Preheat the oven to 400°F and line a baking sheet with parchment paper.
Add flour, sugar, salt, baking soda and baking powder to a medium mixing bowl and mix to combine.
Toss the cubed butter in the flour mixture and work it into the flour with the tip of your fingers until about large pea size.
In a measuring cup, add buttermilk, egg and vanilla extract and beat to combine.
Make a well in the middle of the flour mixture and pour in the liquid mixture, reserving about 1 1/2 tablespoons to use as egg wash.
Fold with a spatula or wooden spoon until a wet dough forms.
Turn the dough out onto a well-floured board, fold it over itself a few times, and shape into a circle about 1” thick.
Cut into 8 scones.
Place the scones on the prepared baking sheet, brush the top and sides with the reserved egg wash, and sprinkle generously with turbinado sugar.
Bake for 19 - 20 minutes until golden brown.
Let cool completely on a wire rack.