Prepare Your Oven and Ingredients: Preheat your oven to 220°C (200°C fan). Line a large baking sheet with parchment paper. In a large bowl, whisk together the self-raising flour, salt, and baking powder.

Rub in the Butter: Add the cold, cubed butter to the flour mixture. Using your fingertips, rub the butter into the flour until the mixture resembles coarse breadcrumbs. Work quickly to prevent the butter from melting. If you're using my frozen butter tip, simply stir the grated butter through the flour.

Add Flavourings: Stir in the caster sugar and the lemon zest. Then, very gently, fold in the frozen raspberries. Be careful not to crush them; you want them to remain whole.

Form the Dough: Make a well in the centre of your dry ingredients and pour in the cold buttermilk. Use a palette knife or a regular dinner knife to mix everything together until a soft, slightly sticky dough just begins to form. Do not overmix! I've tried many methods, but this one gives me the perfect rise every single time.

Shape and Cut the Scones: Tip the dough out onto a lightly floured surface. Gently bring it together with your hands and pat it out into a round, about 2.5cm (1 inch) thick. Use a 6cm round cutter to stamp out your scones. Push the cutter straight down and pull it straight up without twisting to ensure an even rise. Re-pat the scraps gently to cut out more scones until all the dough is used.

Bake to Perfection: Arrange the scones on your prepared baking sheet, leaving a little space between them. Brush the tops (but not the sides) with the beaten egg. Bake for 12-15 minutes, until well-risen and a beautiful golden-brown on top.

Cool and Glaze: Transfer the warm scones to a wire rack to cool slightly. While they are cooling, whisk together the sifted icing sugar and lemon juice in a small bowl to create a smooth, pourable glaze. Drizzle the glaze over the slightly warm scones and leave to set for a few minutes before serving.