To make the base begin by adding the walnuts and salt to your food processor.
Blitz until they form a light crumb consistency.
Add the cacao powder and blend for another minute to combine.
Lastly add the dates and cashew butter and blend further for a couple of minutes until the mixture starts to stick together to form a dough.
Line your baking dish/lunch box with parchment paper and press the brownie dough evenly into the base of the pan.
Alternatively you can roll the brownie dough out between 2 sheets of parchment paper using a rolling pin.
Set the brownie dough aside in the fridge.
For the pumpkin frosting, add all your ingredients to a high speed blender and blitz until smooth and creamy.
Transfer the frosting to a bowl, cover and refrigerate for at least an hour. The mixture should thicken slightly, if it is still runny, place it in the freezer for about 30 minutes.
Stir the icing and ice the top of the brownies using a spatula.
Refrigerate the brownies for another hour.
Cut the brownie into serving sizes and top with dark chocolate drops.