In a 3-quart saucepan (or something similar), toss in butter, sugar, cocoa powder, and milk. Heat it up on medium heat and keep whisking until your butter melts.

Once it's all smooth, bring it to a gentle boil. Let it bubble away without stirring for a minute, then remove it from the heat.

Mix in peanut butter and vanilla until well combined, then stir in your oats with a pinch of salt. Let it sit for about 5 minutes. Line a couple of baking sheets with silicone mats or parchment paper. (Make sure your fridge has enough space for the trays).

Drop dollops of the dough onto your lined sheets with a cookie scoop or tablespoon. If you like, gently press them down with a spoon. Keep going until all the dough is used up.

Pop them into the fridge for about half an hour to 1 hour to firm up. Once they're set, take them out and dig in.