01 - Preheat the oven to 350°F and line a 9 x 13 inch baking tin with parchment paper.
02 - In a large bowl, cream the softened butter with caster sugar until pale and fluffy.
03 - Beat in the eggs one at a time, mixing thoroughly after each addition.
04 - Gently fold in self-raising flour, poppy seeds, lemon zest, vanilla extract, and salt, then stir in the milk until evenly combined.
05 - Pour the batter into the prepared tin and smooth the surface evenly.
06 - Bake for 28 to 32 minutes until golden and a skewer inserted into the center comes out clean.
07 - While baking, combine lemon juice with icing sugar to make the drizzle.
08 - Immediately after baking, pierce holes all over the hot cake with a skewer and pour the lemon drizzle evenly over it.
09 - Allow the cake to cool completely in the tin before cutting into 12 squares to serve.