Line a 20cm x 20cm baking tin with parchment paper. Save any parchment paper off cuts.
In a large sauce pan melt the butter with the condensed milk.
The second the butter has melted and mixed through the condensed milk, take it off the heat and stir in the chocolate until completely melted and combined.
Add in the cranberries, white chocolate, biscuits, mini marshmallows and orange zest. Stir with a wooden spoon until completely combined.
Tumble the mix out into the lined baking tin and press down using the parchment paper off cuts. Drizzle with white chocolate diagonally across the tray.
Cover and allow to set in the fridge for up to 1-2 hours.
Recipe courtesy of Donal Skehan