Preheat your oven to 180°C (350°F). Grease a 23cm (9-inch) round cake tin and line it with parchment paper for easy removal.
In a large mixing bowl, beat the softened butter and caster sugar together using an electric mixer or whisk until the mixture is pale, fluffy, and slightly increased in volume—about 3-4 minutes. You should hear a gentle swishing sound and see a light, creamy texture.
Add the eggs one at a time, beating well after each addition. This helps incorporate air and keeps the batter smooth and cohesive. Scrape down the sides of the bowl as needed.
Stir in the lemon zest and lemon juice, allowing the fragrant citrus aroma to fill the kitchen. The mixture should look bright and slightly glossy.
Sift the plain flour and baking powder into the bowl to ensure an even, airy batter. Gently fold the dry ingredients into the wet using a spatula or a low-speed mixer, just until combined. Be careful not to overmix, as this can make the cake dense.
Pour the batter into your prepared cake tin, smoothing the top with a spatula so it’s level. Place it in the oven and bake for about 35-40 minutes, until the cake is golden and a skewer inserted into the center comes out clean.
While the cake is baking, prepare the lemon glaze by mixing the icing sugar with 3 tablespoons lemon juice until smooth. The glaze should be glossy and slightly thickened but pourable.
Once baked, let the cake cool in the tin for about 10 minutes, then transfer it to a wire rack. While it’s still warm, poke small holes across the surface with a skewer or fork.
Pour the lemon glaze evenly over the warm cake, allowing it to seep into the holes and coat the surface with a shiny, citrusy layer. Let the glaze set for at least 20 minutes before slicing.
Once the glaze has set and the cake is cool, slice it into portions. The final cake should be tender, moist, with a bright lemon aroma and a glossy, tangy surface ready to serve.
