Spinach, chard and chickpea puff pie

Ingredients

• 2 tbsp olive oil
• 2 large onions, finely sliced
• 200g chard, stalks and leaves separated
• 520g young leaf spinach
• 6 garlic cloves, finely sliced
• 1 tsp chilli flakes or pul biber
• 6 medium pickled onions, drained
• 700g jar chickpeas (or 2 x 400g cans chickpeas), drained
• 1 tsp ground cumin
• 500g block puff pastry (choose vegan if needed)
• Plain flour for dusting
• 2 tbsp milk alternative (or 1 small free-range egg, beaten)
• Specialist kit
• 20cm x 26cm baking tin or oven dish