1.Preheat oven to 200°C/400°F. Oil 1.25-litre (5-cup), 8cm x 20cm (3¼-inch x 8-inch) loaf pan; line base and two long sides with baking paper, extending paper 5cm (2 inches) over sides.
2.Line base and sides of pan with prosciutto, slightly overlapping the slices and allowing overhang on long sides of pan.
3.Chop chicken into 2cm (¾-inch) pieces. Process half the chicken until minced finely. Combine minced chicken, chopped chicken, nuts, mustard, rind and parsley in large bowl.
4.Spoon chicken mixture into pan, pressing firmly into sides and corners. Fold prosciutto slices over to cover chicken mixture. Fold baking paper over prosciutto; cover pan tightly with foil.
5.Place pan in medium baking dish. Pour enough boiling water into dish to come halfway up side of pan.
6.Bake terrine 1 hour. Remove pan from water; carefully drain juices from pan. Cool, then weight with another dish filled with heavy cans. Refrigerate 3 hours or overnight.
7.Turn terrine onto plate; slice thickly to serve.
You can make the terrine up to two days ahead of time.Note