For the plum cake, beat the egg whites with a pinch of salt until stiff. Beat the egg yolks with the powdered sugar until foamy. Add spices, rum and oil and stir again.
Mix in the flour, stir in 1 shot of mineral water and fold in the snow. Pour into a greased and floured mold and top with halved plums.
Place a small piece of marzipan on each plum half. Bake at approx. 170 °C.