01 -
Line a 9x13 pan with some parchment or wax paper.
02 -
In a large pot, stir together the butter, sugar, and milk, then set it on medium heat.
03 -
Let it boil until it reaches 234° (takes roughly 5 minutes).
04 -
Remove from the stove and stir in chocolate until it's creamy and blended well.
05 -
Toss in the vanilla, nuts, and marshmallows and stir everything together.
06 -
Pour the mixture into your prepared pan and spread it out evenly.
07 -
Leave it to harden for 4 hours, or chill it in the fridge to speed it up.
08 -
Cut into pieces and serve at room temperature.