1. Preheat oven to 180℃. Grease cake tin with butter or line with baking paper.
2. Beat butter and sugar until fluffy. Add eggs and mix well. Grate lemon and fold into the mixture. Add flour, salt and baking soda. Mix ingredients to create a smooth batter and stir in milk last.
3. Pour the batter into the cake tin, smooth down (e.g. using the back of a spoon) and bake for 40-45 min until it no longer sticks to the blade of a knife.
4. In the meantime, make the icing: mix lemon juice and powdered sugar until the mixture is smooth and white. Add additional lemon juice or powdered sugar as needed.
5. Once the cake has fully cooled, release it from the tin, glaze it with the icing and decorate it with a slice of lemon.