Place the peanuts into a larger bowl along with the three nuts butter, dulce de lèche caramel sauce, marshmallows and some of the white chopped chocolate (the 50g that needs chopping).
Melt the dark chocolate either into a small bowl over boiling water or in the microwave, if you have or use one. If the chocolate is too hot allow it to cool for 2 minutes. This has to be melted but not super hot as it will melt the marshmallows.
Melt the white chocolate (see recipe notes for tips) and add to the chocolate and peanuts mixture. Stir it in slightly if you want some white chocolate into larger lumps or stir more for thinner white chocolate threads.
Pour the dark melted chocolate over the other ingredients already in the bowl. Give it all a good stir.
Overlay a dish of your choice (I used a porcelain dish 15x10cm) with one layer of clingfilm.
Pour over the chocolate mix, level it with a spatula, it is lumpy but just level it to make sure that the chocolate has evenly gone into all the corners and has filled the bottom of the dish properly and evenly.
Place in the fridge for a minimum of 20 minutes or 10 minutes in the freezer if you are in a hurry, and I am sure you are as it is hard to wait...;-)
After it sets you can keep it out of the fridge and I recommend that before attempting to cut it let it be out of the fridge for a while so cutting it is easier. (See recipe notes).