Melt the milk chocolate in a jug or small bowl in the microwave in 30-second bursts (or in a bowl over a saucepan of simmering water, making sure the water doesn’t touch the bottom of the bowl).
Pour and spread the chocolate on a baking tray covered with baking paper. Pop the tray in the freezer for a few minutes to begin to harden.
Meanwhile, melt the white chocolate, then pour / spread over the top of the milk chocolate. Decorate as you wish.
Leave to cool and harden completely (you can speed this process up by popping into the fridge for a short while), then break the bark up into pieces.
*I like to lightly crush the chocolate mini eggs before sprinkling over the chocolate. I pop them into a clear bag and hit them with the end of a rolling pin. I tried doing this in a food processor but found they get totally obliterated rather than just broken up!If you prefer you can swirl the white chocolate into the milk before decorating - this works just as well as keeping the layers separate.