Line an 8" x 8" tin with parchment paper and set aside whilst making the fudge.
Melt the condensed milk and dark chocolate together either in a saucepan on the hob or in short bursts in the microwave until melted. Stir until smooth, then transfer to the prepared tin, spreading out evenly and levelling the top. Place in the fridge whilst preparing the caramel layer.
In a clean bowl or saucepan, melt the caramels down with 1.5 tbsp water until smooth. Tip in the peanuts and fold together to evenly coat the nuts.
Remove the tin from the fridge and place blobs of the peanut caramel on top of the fudge. Spread out into an even layer, pushing into the corners, then level the top. Return the tin to the fridge.
In a small microwave safe bowl, melt the milk chocolate in short bursts until smooth. Remove the tin from the fridge and pour the melted chocolate over the caramel peanut layer. Spread out evenly, then shake the tin a little to smooth out the top of the chocolate. Chill again to set for a few hours or ideally overnight. Once set, cut into squares and serve. Enjoy!