• Preheat the oven at 120°C/ 250°F.

For the cake layers:

• Lightly toast the cashews in a frying pan until slightly golden and roughly chop them in a food processor.
• Place the cashews in a bowl and add the flour and sugar. Mix everything together and set the bowl aside.
  
• Beat the egg whites with a hand mixer. (You'll need room temperature eggs for this - preferably kept at room temp overnight, if possible). Add a pinch of salt and gradually incorporate 180g (3/4 cup) of sugar until you get a smooth and glossy meringue.
  
• Gradually incorporate the cashew mixture into the meringue, mixing with a spatula with upward movements.
• Divide the mixture into two 20 cm (8-inch) cake pans. You can set aside 2-3 tablespoons of the meringue and bake them separately (we'll use this for decorating later) and place in the oven for 2 hours.
• Once the meringue layers are done, leave them to set for 24 hours.

For the buttercream:

• In a bowl, add the sugar, egg yolks and milk and combine using a whisk until smooth and homogenous. Then, pass the mixture through a sieve into a thick-bottomed pan. Place the pan over medium heat and stir continuously as the custard forms.
• Once the liquid starts to boil, continue stirring for another 2 minutes, then take off the heat.
• Place the custard into a bowl, cover with plastic film and leave to cool completely.
• Once cooled, we can prepare the cream. In a separate bowl, whisk the butter with a mixer until creamy and airy, then gradually add the cooled custard in batches. Make sure both the butter and the custard are at the same temperature so the texture doesn't change.
• Scoop out about a third of the cream into another bowl and combine it with a tablespoon of cocoa powder. This will be used to frost the top and sides of the cake.
• Add 2-3 tablespoons of the remaining white cream into a piping bag. We'll use this in the final step for decorating.

For the assemmbly:

• Spread the white cream over one of the meringue cake layers and top with the second layer. Cover the cake with the cocoa cream on top and the sides.
  
• Grind the 2-3 tablespoons of meringue we baked separately in a food processor until you get a coarse "biscuit crumble"-like texture. (You can also use extra crushed cashews or other nuts for this step, if preferred.)
• Press the meringue crumbs gently onto the sides and sprinkle on top of the cake.
• Finally use the buttercream set aside earlier in the piping bag to decorate the cake however you like.
• Leave the cake at room temperature for another 2 hours then place in the fridge overnight.
• Enjoy!