Start by greasing a 20 centimetre by 30 centimeter lamington pan. Then line the base and two long sides with baking paper allowing the sides to overhang.
To make the raspberry puree combine the raspberries and maple syrup in a saucepan over medium heat. Cook stirring for 5 minutes or until the raspberries break down. Strain the mixture through a fine sieve into a heatproof bowl then discard the solids.
Next place the oats, cashews, coconut and dates in a food processor and process until finely chopped. Add the coconut oil, maple syrup and salt. Process until the mixture holds together when pinched. Spoon into the prepared pan and press evenly over the base. Pop in the freezer to set for 30 minutes. Place the bananas in a food processor and process until smooth. Add the frozen dessert and process until smooth and well combined.
Transfer the banana mixture into a large bowl, add half the raspberry puree and fold to marble, spoon over the oat mixture in the prepared pan and top with dollops of the remaining raspberry puree. Use a skewer to gently marble then pop in the freezer for 4 hours or until firm.
Transfer the slice to a clean work surface and cut into bars. Sprinkle with the trail mix and pistachio. Top with the chopped fruit and serve immediately. Try swapping the raspberry puree for peach or blueberry puree for the perfect treat to enjoy on warm summer days.