Rhubarb and Raspberry Cobbler

Ingredients

• 400 g rhubarb, cut into 4 centimetre pieces
• 400 g raspberries
• 1 tbsp cornflour
• 175 g caster sugar, divided
• Zest and juice of 1 orange
• 225 g self-raising flour, plus extra for dusting
• Pinch of salt
• 50 g unsalted butter, cubed
• 120 mL full cream milk, plus extra to brush
• 1 tbsp golden syrup
• 1 tsp water
• 50 g pistachios, chopped
• Vanilla custard to serve