Cut the almonds into halves with a sharp knife. Chop walnuts to roughly the same size. Cut marshmallows into halves. Mix together all ingredients except chocolate in a bowl.
To melt the chocolate, break milk and dark blocks into pieces and place together in a heatproof bowl (glass is best). Place the bowl in a saucepan of hot water on the stove and gently warm it until melted, stirring occasionally. Do not allow the water to boil. (you could slco do this in the microwave.)
Pour the melted chocolate over the mixed dry ingredients and stir together with a wooden spoon or spatula. Pour the mixture into a 20 x 20 x 5 am square tin lined with baking paper. Refrigerate. Cut into squares and enjoy!