Melt the margarine and let it cool down. Peel, core, quarter and slice the apples. Core and cut the plums into eighths.
Separate the eggs from the yolks (keep there) and place the egg whites in a mixing bowl. Add the sugar while stirring and beat until frothy. Then mix the flour with the baking powder and slowly stir into the egg white and sugar mixture one after the other together with the margarine or butter and the egg yolk.
Grease 1 large, rectangular baking sheet and sprinkle with breadcrumbs to prevent the cake from sticking. Then put the dough in the baking sheet and alternately press the plums and apples into the dough in straight rows. Place in the oven at 200 ° C for 40 minutes.
After cooling, sprinkle the cake with powdered sugar.