Grease a slice tin (approx 28 x 18cm) and line with baking paper, allowing the baking paper to overhang each side (to assist with removal once it's ready to slice).
Melt dark chocolate (by chopping, placing in a heatproof bowl and microwaving for 30 seconds at a time, stirring after each time).
Pour chocolate into the slice tin and place into fridge to set.
Place remaining ingredients in a mixing bowl and stir to combine.
Pour mixture onto chocolate layer in slice tin. Use the back of a metal spoon to even out the mixture and press into the chocolate layer. Wet hands and use your hands to push the mixture quite firmly into the tin.
Bake in a moderate oven for 15 minutes.
Remove from oven and allow to cool completely.
Lift the slice from the tray using the baking paper edges and cut into 24 squares using a sharp knife.
Notes
Storing: Store this slice in an airtight container at room temperature for up to 7 days.Freezing: You can also freeze it – wrap well and place in an airtight container before freezing for up to 2 months.Nutrition: The nutrition information is an automatically generated estimate and is not guaranteed to be accurate.