For brown sugar pastry, beat butter and brown sugar, using an electric mixer for 5 minutes or until pale, then add eggs and beat to combine. Add flour, beat until just combined, turn onto a lightly floured work surface, form into a disc, wrap in plastic wrap and refrigerate for 2 hours.
Meanwhile, rinse rhubarb in a colander and transfer to a heavy-based saucepan. Add brown sugar, vanilla seeds and juices and stir over medium heat until sugar dissolves. Bring to the boil, reduce heat to medium and cook for 12-15 minutes or until rhubarb is soft and liquid is reduced. Set aside until required.
Preheat oven to 180C. Roll pastry on a lightly floured surface to 2mm thick and use to line six 7.5cm-diameter x 4cm-deep pie pans (see note), trim edges and refrigerate for 30 minutes. Line pastry-lined pans with baking paper, weigh down with pastry weights or rice and bake blind for 10 minutes, then remove paper and pastry weights and bake for another 10 minutes or until golden and crisp. Cool for 5 minutes in pans, then remove from pans and place on a baking tray. Spoon warm rhubarb mixture into pastry cases and set aside.
For Italian meringue, combine sugars and ¼ cup water in a heavy-based saucepan and stir over low heat until sugar dissolves. Increase heat to high and cook until syrup reaches 115C on a sugar thermometer, then remove from heat. Meanwhile, using an electric mixer, whisk eggwhites until soft peaks form, then, with motor running, slowly add hot syrup and whisk for 5 minutes. Spoon meringue over rhubarb, forming into peaks. Place pies under a hot grill for
2-3 minutes or until meringue is golden or use a blowtorch to brown meringue lightly. Serve immediately with remaining rhubarb passed separately.
Note If you're unable to find pie pans of this
measurement, use individual fluted tart cases instead (they'll hold