1.Grease 8cm x 26cm bar pan; line base with baking paper, extending paper 5cm over long sides.
2.Stir condensed milk and butter in small saucepan over low heat until smooth. Remove from heat; add chocolate, stir until smooth.
3.Break biscuits into small pieces; place in large bowl with cranberries and nuts. Stir in chocolate mixture.
4.Spread mixture into pan, cover; refrigerate about 3 hours or overnight until firm. Cut into 12 slices.