Line a 2lb/900g loaf tin (loaf pan), I like to use loaf tin liners for quickness (you could use a brownie pan instead of a loaf tin).
Add the dates (without stones) to a food processor or blender with the vanilla extract and pulse dates into a paste. No blender or food processor? See notes below.
Next, add the oats, cocoa powder (or cacao powder) and salt.
Finally, add the peanut butter and pulse the mixture until you have a slightly grainy mixture.
Spoon it into your lined loaf tin (or brownie pan) and press down with the back of a spoon or rubber spatula. You want it to be well compressed and as even as possible.
Melt the chocolate in a microwave or bain marie (see notes) and spread it in an even layer across the brownie batter layer.
Sprinkle some salted peanuts across the top and pop in the fridge to chill and for the chocolate to set.
Slice and enjoy!
Notes
If you don't have a food processor or blender, you can mince the dates finely with a sharp knife, then mash with the vanilla extract, add to a mixing bowl and mix the other ingredients in well.
You can use another nut butter, like almond butter or sun butter (sunflower seed butter) if you have a nut allergy.
Melt the chocolate in a bowl in the microwave (mine is 800 watts and it takes about a minute, but if yours is less powerful, it could take a little longer or more powerful, it will melt quicker, just keep an eye on it so it doesn't burn).
Alternatively, melt in a bain marie (bowl suspended over a pot of simmering water).
The peanuts on top are optional, but give a nice salty bite against the sweetness.
Store in an airtight container in the fridge for up to a week.