2 bunches rhubarb, green tops discarded
¼ cup of water
2 tsp vanilla extract
1 cup caster sugar
Melted butter, for greasing
125g unsalted butter, cubed
1½ cups self-raising flour, sifted
½ cup milk
100g white chocolate, finely chopped
Pure icing sugar, for dusting
Pouring or whipped cream, to serve
½ cup plain flour
½ cup white sugar
1½ cups (150g) walnuts, finely chopped
80g unsalted butter, melted
Cut rhubarb into 2cm pieces. Put in a saucepan with water, vanilla and half the sugar and bring to simmer. Stir until sugar dissolves. Cover and cook for 5-7 minutes or until rhubarb is soft. Strain through a sieve and reserve the syrup. Put rhubarb into a bowl and chill for 30 minutes.
Preheat oven to 180°C. Grease a 24cm x 5cm-deep flan tin with a removable base or a 24cm springform tin with melted butter. Beat butter and remaining sugar in the small bowl of an electric mixer until pale and creamy. Add eggs, beating between each addition.
To make walnut crumble; combine flour, sugar and walnuts in a bowl, then add butter and stir to combine.
Transfer butter, egg and sugar mixture to a large bowl, then stir in flour and milk in two batches. Fold in chocolate. Spread white chocolate mixture in tin, then put tin on an oven tray. Spread rhubarb over the top and sprinkle with crumble. Bake for 1 hour or until a skewer inserted into cake comes out clean. Allow to cool, then dust with icing sugar. Serve with cream and reserved syrup.