Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine the flour, sugar, baking powder, baking soda, salt, and lemon zest. Mix well to ensure even distribution of dry ingredients.
Add the cold, cubed butter to the flour mixture. Use a pastry cutter or your fingers to work the butter into the flour until the mixture resembles coarse crumbs.
Make a well in the center of the mixture and pour in the buttermilk. Gently stir until just combined, being careful not to overmix.
Fold in the raspberries gently, ensuring they are evenly distributed throughout the dough without crushing them.
Turn the dough out onto a lightly floured surface and shape into a disc about 1-inch thick. Cut the disc into 8 wedges or use a cookie cutter for round shapes.
Place the scones on the prepared baking sheet. Brush the tops with the beaten egg for a golden finish.
Bake for 15-20 minutes or until golden brown and a toothpick inserted into the center comes out clean.
Allow the scones to cool on the baking sheet for about 5 minutes before transferring them to a wire rack.
Notes
Serve warm, dusted with powdered sugar, and accompanied by clotted cream or lemon curd.