Line a 20cm (base) square cake pan with baking paper, allowing an overhang at two opposite edges so you can lift the cake out. Remove the ice cream from the freezer and allow to soften slightly for 5-10 minutes.
Place the biscuits into a food processor and pulse until coarsely chopped. Transfer to a bowl, add the coconut and stir to combine. Spoon half the biscuit mixture (1 cup) over the base of the cake pan, spreading to cover.
Spoon the caramel into a microwave safe bowl, heat, uncovered, for 2-3 minutes on Medium/50%, stirring every minute until warm. Drizzle half the caramel over the biscuit mixture. Carefully top with half the ice cream, don’t smooth the surface.
Sprinkle over the remaining biscuit mixture. Drizzle over the remaining caramel and top with remaining ice cream. Smooth the top surface. Press the grapes into the ice cream. Cover and freeze overnight.
Lift the ice cream cake out of the pan, cut into squares and serve drizzled with extra warmed caramel if desired.
TipTip: If you don’t have a 20cm square cake pan you can use a 22cm round cake pan.