Crayfish Pies

Pastry

• 175 g plain flour, plus extra for dusting
• 90 g unsalted butter, cold, diced
• 1 pinch fine sea salt
• 1 egg yolk, from medium egg
• 1 - 2 Tbsp water

Filling

• 40 g unsalted butter, diced
• 1 garlic clove
• 6 spring onions, cut in pieces (3 cm)
• ½ green pepper, quartered
• 1 celery stalk, quartered
• 200 g crayfish tails, cooked
  or 200 g prawns, cooked, peeled
• 20 g plain flour
• 220 g whole milk
• ¼ tsp Cajun spice mix
• ¼ tsp fine sea salt
• 1 pinch ground black pepper
• fresh parsley leaves, roughly chopped, for garnishing (optional)