Melt butter in a pot. Separate eggs. Beat the egg whites until stiff, adding 100 g sugar and 1 pinch of salt. Whisk egg yolks, 1 tbsp rum and 100 g sugar with the whisk of the hand mixer for about 2 minutes until creamy. Mix flour, baking powder and coconut flakes and stir in alternately with the butter. Fold in the last beaten egg white
Pour the mixture into a baking tray (32 x 39 cm) lined with baking paper and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 20 minutes. Take out the cake and let it cool down
Cut out 16 circles (each approx. 7 cm Ø) from the cake. Use the remaining dough for other purposes. Peel the pineapple and cut 16 thin slices from the middle. Mix mascarpone, 50 g icing sugar, pineapple juice and 1 tbsp. rum to a smooth cream. Put 1 slice of pineapple, then mascarpone cream and another 1 slice of pineapple on 8 circles. Finish with one cake circle each
Squeeze the lime. Mix 150 g icing sugar and 1-2 tablespoons lime juice to a thick icing. Cover the cake surface with the icing and decorate with sugar decoration. Put the cake in a cool place for about 1 hour and let it dry
waiting time approx. 1 1/2 hours
Tip: Dough remains can also be easily processed into rum balls