Line a 8β x 12β (22cm x 32cm) rectangle baking pan with parchment paper and set aside.
Crush biscuits in a food processor or by hand, adding the biscuits to a ziplock bag and crushing them with a wooden spoon. Leaving some larger chunks intact. Scoop out approx. 1/2 worth of crushed biscuits to save for the topping. Set both aside.
Prepare a double boiler with a heat proof mixing bowl over simmering water.
Add chocolate and butter to the bowl and gently melt, stirring occasionally.
Once completely melted and smooth, slowly pour in condensed milk, mixing until well combined. Remove from heat.
Add main measurement of crushed biscuits into the mixture and gently fold until just combined, still leaving some white streaks.
Pour mixture into lined pan, smoothing out evenly with a spatula.
Sprinkle over extra crushed biscuits.
Set in the refrigerator for 2-3 hours or overnight until completely set. Itβs texture will remain fudgy, not completely hardened.
Remove from pan and slice into squares.
Serve and enjoy!