Spread about 1½ teaspoons of jam on each of the un-glazed side of 18 Lattice biscuits. Place in a single layer, jam side up on a tray and freeze until firm (about 45 minutes). Line a deep 20cm square pan with baking paper, allowing 5cm overhang to help lifting out.
Place ice cream in a large bowl of electric mixer and beat on low speed for 1 minute or until softened. Fold through peanut butter with a spoon.
Place ½ jam biscuits in base of prepared pan jam side up. This should be a tight fit. Spoon peanut butter ice cream over biscuits and smooth the top flat. Top with remaining biscuits, jam side down. Cover with plastic wrap and freeze for 4 hours or overnight.
Using baking paper overhang, lift ice cream on to a board. Use biscuits as a guide to cut 9 ice cream squares.
Place peanuts in a low sided bowl, press each ice cream side of the squares into nuts. Pat gently with your hand to help nuts adhere. Squares can be frozen individually, wrapped in plastic wrap or layered between baking paper in an airtight container, store in freezer for up to 2 weeks.