By Kit Chapman
To make the white chocolate mousse, melt the chocolate and milk slowly in a pan. Whisk the egg yolks and sugar until pale, then add to the chocolate mixture. Dissolve the gelatine in the water over gentle heat and add to the mixture. Place the mixture over a bowl of ice until beginning to set. Whisk the yoghurt and cream together, add to the mixture and whisk until smooth.
To make the d