Wash 1 lime hot, dab dry and finely grate the peel. Squeeze both limes. Mix about 6 tbsp. juice, grated zest, rum and sugar. Wash the mint, dab off the leaves.
Cut the melon into thick slices and dice the flesh (see photo). Mix melon, mint and lime marinade about 45 minutes before serving. Divide into four dessert bowls and freeze.
Mix yoghurt and vanilla sugar. Finely crumble the Amarettini. Arrange the melon mix with 1 blob of yoghurt and sprinkle the amarettini crumbs on top.