Line a 28cm x 18cm slice tin.
Place biscuits in a zip-lock bag and squeeze to remove excess air. Place on hard surface and hit with rolling pin to crush biscuits - make sure not to crush too fine - you want some larger chunks left in there to create that hedgehog crunch.
Transfer crushed biscuits into a large bowl. Add coconut and cocoa. Stir to combine and set aside.
In a small saucepan, combine dark chocolate, butter and sweetened condensed milk. Stir over low heat until melted and fully combined. Cool mixture for 1-2 minutes.
Pour chocolate mixture into dry ingredients. Stir to combine.
Press mixture firmly into prepared pan. Refrigerate for 30 minutes or until firm.
Once the base is firm, place dark chocolate in a microwave safe bowl. Microwave in 30 second intervals until melted, stirring between each allotment. Add vegetable oil and stir until smooth.
Pour chocolate topping over slice and spread evenly. Refrigerate for 30-45 minutes or until set. Cut into squares to serve.
