1. Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it.
2. In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and lemon zest
3. Add the cold cubed butter to the dry ingredients. Using a pastry cutter or your fingertips, cut the butter into the flour mixture until it resembles coarse crumbs.
4. In a separate small bowl, whisk together the buttermilk, lemon extract and vanilla extract.
5. Make a well in the center of the dry ingredients and pour in the buttermilk mixture. Gently stir until the dough starts to come together. Be careful not to overmix.
6. Transfer the dough onto a lightly floured surface. Gently knead it a few times until it forms a cohesive ball.
7. Pat the dough into a circle about 1 inch thick. Using a sharp knife or a biscuit cutter, cut the dough into triangular scones.
8. Place the scones onto the prepared baking sheet, leaving some space between them. Brush the tops of the scones with the beaten egg wash and sprinkle some granulated sugar on top for a nice crunch.
9. Bake in the preheated oven for about 15-18 minutes or until the scones are golden brown and cooked through.
10. While your scones are baking, mix together ingredients for the lemon glaze to have ready to drizzle over the scone. 
11. Remove scones from the oven and transfer the scones to a wire rack to cool slightly. Drizzle with glaze and top with lemon zest if desired. Serve warm or at room temperature.

Tip for lemon glaze: If you want a stronger lemon flavor, you can add more lemon juice or zest to the glaze. Conversely, if you prefer a milder flavor, reduce the amount of lemon juice and zest.