Line a square baking tin (if you use baking paper) and preheat the oven to 175°C.
Melt the coconut oil in a pan. Turn off the heat, add the almond pulp and stir to combine.
In a separate bowl, combine the sugar, cocoa powder and flour, and mix well. Add to the pan and stir in. It might seem really dry at first, but it will blend in.
Once combined, add the vanilla essence, salt and walnuts (or delicious thing of your choice).
In a tall cylinder, whisk the aquafaba to form stiff peaks. (This will take longer than you think.) If using a stick blender with a whisk attachment it takes at least 5 minutes of constant whisking.
Add the aquafaba to the brownie mixture in the pan, slowly folding to incorporate with as little stirring as possible.
Once fully mixed, pour into the baking tray.
Sprinkle the toppings on (if using) and bake in the oven for 20 – 25 minutes until the top is dry.
Store in the fridge or freeze for later.