To make the caramel:
Soak the cashews in boiling water for 20+ mins (the longer the better)
Blend with the plant-based milk until smooth (add extra dashes of milk if it's stubborn to blend)
Add the sugar to a dry pan on high heat
Stir continuously until it forms a brown viscous liquid
Remove from the heat and add the cashew cream
Stir VERY QUICKLY to combine & prevent any lumps forming
Store in the fridge until ready to use
Preheat the oven to 200'C/180'C fan
In a large bowl, combine the brownie mix, margarine and boiling water
Transfer the mix to a lined baking tin so that the mix is 1 inch deep
Swirl in your vegan caramel, sprinkle on some salt and bake for 20-25 minutes.
Allow to cool before cutting.