Preheat oven to 160C/325F and grease and line a 2lb loaf tin.

Place butter/marg, sugar and lemon zest into a large bowl or the bowl of your stand mixer. Beat until light and fluffy, about 2 minutes on med-high speed.

Add in the eggs and vanilla extract and mix until well incorporated, scraping down sides as necessary.

Add in the flour, baking powder and salt, if using, and mix on low until it starts to incorporate. Then stop mixing and add in the milk and mix on a medium speed until well combined and smooth.

Tip the batter into your lined loaf tin and smooth until level with a spatula/wooden spoon.

Place in the oven for 65-75 minutes, until risen, golden and an inserted skewer into the centre comes out clean.

Whilst the cake is baking, place 1/2 cup sugar and lemon juice into a jug and place it by the side of your oven to warm slightly. (If you can, if not, microwave it for 30 seconds just before pouring).

Once the cake is baked, remove from the oven and use a skewer to poke holes all over the top of the cake (push the skewer all the way in). Then slowly pour your lemon juice and sugar mix all over the cake, allowing it to absorb before adding more - you don't want to pour quickly and for it all to flood out!!

Leave to cool in the tin completely before transferring to a cutting board to slice into 12-14 slices.

Cake will keep in an airtight container, at room temperature, for 4 days.