Let the butter and eggs return to room temperature. Sift together the cake flour and baking powder. Grease the cake tin with butter and dust with flour. Preheat the oven to 180°C.

Add the softened butter to a bowl and cream with a whisk. Add the sugar and keep mixing until the mixture becomes pale and fluffy.

Add the well-beaten eggs a little at a time, mixing well after each addition. If you add it all at once the mixture tends to separate so be careful. Add the sakura liqueur.

Sift in the powder ingredients and fold in gently with a rubber spatula.

Add 1/4 of the mixture to a separate container and mix well with the sakura-an. Add the lot back into the original mixture and give it a quick stir. Don't mix it too much or you won't get a good marble pattern! Fold in gently.