Note: You'll need to chill this for two-and-a-half hours.
1 bunch rhubarb, chopped
1 ¾ cup caster sugar
1 ¾ cups plain flour
120g butter, chopped, at room temperature
1 tablespoon milk
4 eggs few drops of red food colouring, optional
2 teaspoons vanilla extract
Finely grated zest and juice of 1 small lemon
Preheat oven to 180C (160C fan forced). Line a 20cm x 30cm slice pan with baking paper. Combine rhubarb, ½ cup caster sugar and 2 tablespoons water in a pan. Cook over a medium heat for 10 min or until rhubarb has completely broken down.
Transfer to a blender or food processor and puree until smooth. Set aside to cool. You will need 1 cup of puree for the curd.
Meanwhile, process a further ½ cup caster sugar, 1 ¼ cups flour, butter and milk in a food processor until the mixture comes together. Press into base of prepared pan and bake for 20-25 min or until golden brown. Set aside.
For the rhubarb curd, whisk eggs, remaining ¾ cup caster sugar, rhubarb puree, food colouring, vanilla and lemon zest and juice in a large bowl until well combined. Whisk in the remaining ½ cup plain flour.
Pour the rhubarb curd over the biscuit base and bake for 15-20 min or until rhubarb is set. Let cool to room temperature then chill for 2-3hr or until chilled. Dust with icing sugar and cut into squares or bars to serve.