In a mixing bowl, beat the castor sugar, eggs and zest until fluffy with an electric mixer.
Sieve the flour and baking powder into egg mixture, following with the milk and vanilla essence.
Mix until incorporated and separate the batter into two loaf pans.
Bake for 30 minutes at 170 degrees Celsius.
Halfway through baking time, prepare the syrup by adding the sugar and lemon juice into a small saucepan. Heat it up until the sugar melts and the syrup gets thicker and sticky.
When the lemon loafs are baked, gently pour the hot syrup over the lemon loafs.