Beat the egg white until stiff, adding salt and 125 g sugar. Continue beating until the sugar is dissolved and the mixture is shiny. Line 2 baking trays with baking paper. Spread the meringue mixture in 8 patties on the baking paper.
Spread a little with a spoon, forming a hollow in the middle of each. Leave to dry in the preheated oven (electric cooker: 125 °C/ circulating air: 100 °C/ gas: not suitable) for 1 1/2-2 hours. After about half of the baking time, replace the baking trays once.
Remove and let it cool down. Deseed melons. Use two ball cutters of different sizes to cut out balls from the melons. Wash the mint, dab dry and cut into fine strips. Mix 1 tablespoon of sugar and mint into the melon balls and leave to stand for 15 minutes.
Whip the cream until stiff. Spread the cream on the meringue cake. Put melon balls on top.