Rhubarb, apple and cinnamon cobbler

This recipe is from Australian Gourmet Traveller's August 2007 edition (page 114):

400 g rhubarb, cut into 2cm lengths
3 pink lady apples, peeled, cored and cut into wedges
110 g raw caster sugar
40 g honey
2 tsp cornflour
juice of 1 lemon

For the pastry:

150 g self-raising flour
30 g raw sugar
1 1/2 tsp ground cinnamon
50 g butter, coarsely chopped
90 ml buttermilk, plus extra for brushing

* Preheat the oven to 190C.
* Rinse the rhubarb, drain and transfer to a bowl. Add the apple, sugar, honey, cornflour and lemon juice and stir to combine; then place in a 1.5 litre capacity oven-proof dish.
* For the pastry:
- process flour, 2 tbsp sugar, 1 tsp cinnamon, butter and 1 tsp sea salt in a food processor until mixture resembles fine breadcrumbs.
- add buttermilk and process until mixture forms a dough, then transfer to a lightly floured surface and knead until smooth.
- roll out to 4mm thick and, using a 7 cm-diameter pasty cutter, cut out rounds and arrange over rhubarb mixture, overlapping slightly. Brush tops with a little extra buttermilk.
* Combine remaining sugar and cinnamon in a small bowl, scatter over pasty and bake for 45 - 50 minutes or until fruit is bubbling and pastry is golden and risen.