Start by pre-heating your oven to 180c/350f. Also grease and line a square 8 inch cake tin.

In a pot, add the butter and dark chocolate. Place this onto medium heat and heat, whiles stirring, until it has all melted and you have a smooth mixture. You can also do this in your microwave. Leave this aside to cool down.

In a large bowl, add the eggs and both sugars. Whip these together until the mixture lightens in colour and increases in volume slightly. This should take about 2-3 minutes.

Pour your melted butter/chocolate mixture into this, whisk until combined.

Now add the flour, cocoa powder and salt. Whisk just until you get a smooth batter.

Add this batter into your prepared tin and bake at 180c/350f for around 40 minutes, or until a toothpick inserted into the centre comes out with a few moist crumbs on it.

Once baked, leave this aside whiles you make the rice krispie layer.

In a pot or pan, add the sugar. Place this onto medium heat.

Keep heating this, whiles CONSTANTLY stirring, until all the sugar has melted and turned an amber colour.

Take this off the heat and mix in the softened butter. Then slowly pour in the cream, whiles mixing.

Mix in the salt and vanilla.

Place this back onto medium heat and let this boil for 1-2 minutes, stir this every now and then. This will thicken the caramel slightly and it will also get rid of any lumps that might have formed.

In a large bowl, add the mini marshmallows and pour the hot caramel over this. Mix until the marshmallows have completely melted.

Add the rice krispies into this and mix.

Add this into your tin, on top of the baked brownie. Press this down and smooth it out. This mixture is very sticky, either use a wet palette knife or spatula to press it down, or you can just use wet hands.

Leave this to set up at room temperature for at least an hour, then cut into it and enjoy!