Set the oven temperature to 200°C (Gas mark 6). Line a baking tray with grease proof paper.
In a saucepan, add the water, butter and coconut sugar. Place on a medium heat until the butter has melted. Whisk in the flour until there are no lumps and the mixture is smooth.
Use a wooden spoon and stir the dough over a low heat until a ball is formed. Take off the heat and set aside.
In a bowl, beat up the eggs and add the vanilla extract.
Add a small amount of the egg into the dough, mixing until it is fully combined. Continue adding the egg mixture a little at a time, mixing thoroughly into the dough each time. When finished, the dough should resemble a thick paste.
Add the mixture into a piping bag with a star nozzle.
Pipe the churros onto the grease proof paper. They should be about 12-14cm long.
Place the churros in the oven and bake for 15 minutes. After this time, turn off the oven and leave them in there for a further 10 minutes to help keep their shape.
Place a heatproof bowl over a pan of simmering water, ensuring that the base does not touch the water. Break the dark chocolate into the bowl and allow to melt, stirring occasionally.
Dip the churros into the dark chocolate and coat with the roughly chopped Whitworths Californian walnuts and Whitworths pistachios.