Cheese and onion pie Archive

Ingredients

• 450g/1lb plain flour, plus extra for dusting
• 2 tsp baking powder
• ½ tsp salt
• 120g/4½oz unsalted butter, plus extra for greasing
• 1 free-range egg yolk
• 50g/2oz parmesan cheese (or a similar vegetarian hard cheese), grated
• 120ml/4fl oz water
• 1 free-range egg, beaten, for glazing
• 1 medium potato, peeled and cut into cubes
• 2 onions, finely sliced
• 1 tbsp plain flour
• 50ml/2oz whole milk
• 50ml/2oz double cream
• 150g/5½oz mature cheddar cheese, grated
• ½ tsp English mustard
• ½ tsp cayenne pepper
• salt and freshly ground black pepper