⅓cupchocolate sauce*you can use store bought if you would prefer
⅓cupdark chocolateroughly chopped into chunks
Add cream, condensed milk and peanut butter to the bowl of a stand mixer and using that or a hand mixer, whip the mixture until the peanut butter is combined and the cream is whipped (about 5-6 minutes) The mixture should form soft peaks when you lift the mixer out. Stir through the chocolate chunks, saving some to sprinkle on top.
Pour half of the ice-cream mixture into the container you will freeze it in, swirl through half the chocolate sauce, top with the remaining ice-cream, sauce, sprinkle the extra chocolate on top and freeze for at least 4 hours, or overnight.
Add sugar, cocoa powder & milk to a saucepan and whisk to combine. Bring to the boil over a medium heat, stirring occasionally. You can also use the microwave for this step.
As soon as the sauce reaches the boil, remove from the heat, stir in the butter, vanilla & salt until the butter has melted. Allow to cool before swirling through the ice-cream.
There may be some sauce leftover after you have swirled it through the ice-cream - you can store it in the fridge and re-heat it, or pour it over ice-cream cold. It's also great as a milkshake syrup!