Pear, walnut and ginger pie with vanilla custard

Ingredients

• Pastry and glaze
• 1 cup flour
• 1/2 cup walnuts
• 1 tablespoon sugar
• 1 teaspoon baking powder
• 125 grams butter (cold and cubed)
• 1 tablespoon cold water
• 1 egg white
• 2 tablespoons sugar
• Filling
• 700 grams pears
• 1/3 cup sugar
• 2 tablespoons semolina
• 1 egg yolk, whisked
• 1/3 cup crystallised ginger, roughly chopped
• 1/3 cup walnuts, roughly chopped
• Vanilla custard
• 2 cups milk
• 1 vanilla pod, split lengthways
• 4 egg yolks
• 4 tablespoons sugar