Set your oven to 180°C.
Use 160°C for fan ovens.
This is important.
Grease your tray bake tin well.
Line it with baking parchment.
Push paper into the corners.
Put butter, sugar, and flour in bowl.
Add baking powder and eggs.
Pour in milk and lemon zest.
Beat for two minutes until smooth.
Pour batter into prepared tin.
Spread it evenly with a spoon.
Bake for 35-40 minutes.
The cake should spring back.
It should pull from tin sides.
Mix granulated sugar with lemon juice.
Stir until it is runny.
Remove cake from tin.
Place on wire rack.
Spoon drizzle over warm cake.
Let it soak in.
Wait until cake is cold.
Cut into squares.
Serve and enjoy.