Place eggwhites in a clean, dry bowl. Using a balloon whisk, whisk until frothy. Add icing sugar and peppermint essence. Using a wooden spoon, stir until mixture almost comes together. Using clean hands, bring mixture together to form a ball.
Turn mixture onto a clean surface lightly dusted with icing sugar. Knead until smooth and not sticky. Work in extra icing sugar if necessary. Place mixture between 2 large sheets baking paper lightly dusted with icing sugar. Roll out until 1cm thick.
Line 2 large, flat baking trays with baking paper. Using a 3.5cm round cutter, cut rounds out of dough. Press leftover dough together and repeat. Place rounds on prepared trays. Set aside, uncovered, overnight, turning over once, to allow peppermint creams to dry out.
Half-dip each peppermint cream in melted chocolate (make sure chocolate is not too hot or it will melt the peppermint mixture). Return peppermint creams to trays. Refrigerate until chocolate is set.