Line a 20cm square baking pan with enough baking paper to overlap two sides of the pan
To make the base, place the cacao, oil, dates and 1 cup (150g) cashews in a high-speed blender and whiz to a coarse paste. Spread evenly into the prepared pan, then transfer to the freezer to firm up
For the topping, place all the ingredients in a bowl set over a saucepan of gently simmering water and stir until smooth and combined. Remove the bowl from the heat and cool to room temperature. Pour over the chilled raspberry filling, then return the pan to the freezer to set.
Once the topping has set, remove the pan from the freezer, then, using the baking paper, lift the slice out of the pan. Using a hot knife, cut into 18 bars to serve. Keep frozen or refrigerated until ready to serve.