Melt the chocolate in a large heat-proof bowl over simmering water (making sure that the base of the bowl doesn't touch the water) until the chocolate has completely melted. Set aside to cool.
Meanwhile whisk the egg whites, sugar and salt in a large mixing bowl until stiff peaks have formed.
Beat about a third of the egg whites into the cool chocolate mixture. You don't have to be delicate here: it's just a case of introducing the egg whites to the chocolate roughly.
Next, delicately fold the second third of the egg whites into the bubbly chocolate mixture until well incorporated and it gets lighter.
Finally, when all the white air pockets have gone, fold in the remaining third of egg whites into the chocolate mixture and repeat the delicate folding in technique until the mixture is a uniform texture and colour.
Tip the Maltesers into the bowl and mix in gently, making sure to spread them around evenly, before pouring into the individual serving glasses. Garnish with a few crushed Maltesers and chill in the fridge until set.