Preheat the oven to 180°C (approximately 350°F).
For the batter: Separate eggs. Beat yolks and half the sugar until frothy. Beat egg whites with a pinch of salt until stiff and stir in remaining sugar. Continue to beat until mixture is glossy. Fold whites into yolks. Combine flour and cornstarch, the fold into batter.
Pour batter into a springform pan lined with parchment paper, smooth and bake for about 35 minutes.
Remove and let cool, release from pan and let cool completely on a wire rack.
For the topping: Drain mandarins, set 8 aside and collect juice. Boil 125 ml (approximately .5 cup) of juice and glaze. Remove from heat, stir in fruit and spread onto cake. Let cool completely.
Beat cream until stiff. Spread onto mandarins. Slice and serve with chocolate-covered marshmallows and remaining mandarins.