Preheat your oven to 180 C / Gas 4. Grease an 18cm round cake tin and line with baking parchment.
In a bowl, beat together the sugar and butter until pale and fluffy. Add the eggs one at a time until creamy. Sift in the flour and add the vanilla, if using. Spoon the mixture into the prepared cake tin.
Bake in the preheated oven for 10 to 15 minutes until risen and golden and a skewer inserted into the centre comes out clean. Remove from the oven allow to cool then sit back and enjoy some cake! Yummy!