1.Grease 20cm x 30cm rectangular pan; line base and long sides with baking paper, extending paper 5cm over sides.
2.Chop chocolate coarsely. Combine chocolate, condensed milk and butter in large saucepan; stir over low heat until smooth. Remove from heat; stir in nougat. Pour mixture into pan, smooth surface with a wet spatula. Refrigerate about 3 hours or until firm before cutting.