Preheat the oven to 180C/350F/Gas 4.
For the base, mix the water biscuits, sugar and melted butter together in a bowl, then press the mixture into the base of a 25cm/10in springform cake tin.
For the topping, beat the ricotta, eggs, sugar and honey together in a bowl.
Fold in the crushed pistachios and golden raisins, then spoon the topping mixture onto the base.
Transfer to the oven and bake for an hour, or until set and lightly golden-brown. Remove from the oven and allow to cool completely.
For the sauce, place the honey and pistachios into a pan and heat gently to warm through.
To serve, slice the cake into wedges, pour over the sauce and serve with thick Greek-style yoghurt.