Line a large baking tray with cling film or foil. Cling film is easier to remove once the squares are set but as we are trying to use less plastic I used foil.

In a large sauce pan add in the butter, mini marshmallows and 150g of the milk chocolate broken into chunks. Heat them over a medium heat, stirring occasionally until all fully melted.

Remove the pan from the heat and pour in the Rice Krispies. Stir everything together so it's all evenly combined and then turn out the mixture into the baking tray. Wet your hands and press the mixture down and out to fill the pan. Wet hands will stop the mixture sticking to you.

Sprinkle the chocolate chunks over the surface and gently press them in to the mixture. Melt the remaining 50g of chocolate and drizzle it over the surface. Put the whole pan into the fridge for it to set before removing the cling film/foil and cutting into squares/rectangles. I cut 24 but you could cut bigger squares for a larger snack or you could cut them into bite sized squares.