In a large bowl, crush the Digestive biscuits into small chunks with a few crumbs. Set the bowl aside.
Break the milk chocolate into pieces and melt over low heat in a double boiler or microwave. If you're melting it in the microwave, take it out and stir it every 20 seconds or so to prevent burning.
Add all of the Nutella into the bowl with the melted chocolate and mix well until smooth.
Spoon the melted Nutella mixture into the bowl with the crushed Digestives and mix well. Once all the biscuits are coated in chocolate, press everything into your lined tin. A rubber spatula is useful for pressing it in.
Refrigerate the whole thing for 30-60 minutes until firm. Then just cut into slices and enjoy!
Video
Notes
Store leftovers in an airtight container in the fridge for up to 2 weeks.