Line a rimmed baking sheet with parchment paper. The size of your sheet will determine the thickness of the bark.
In a bowl, combine sugar, half of the raspberries and pistachios. Pour the mixture onto the parchment-lined sheet and smooth out the surface. Add the other half of the raspberries and pistachios, along with cacao nibs, by sprinkling across the surface.
Freeze for about 3-4 hours or until completely firm.
Use a mallet or the back of a wooden spoon or rolling pin to break the bark into smaller pieces.