Pastéis de Nata (Custard Pastries)

Custard

• 180 g sugar
• 50 g plain flour, plus extra for dusting
• 250 g double cream
• 250 g milk
• 5 egg yolks, from medium eggs
• lemon peel, 1 strip
• 1 cinnamon stick

Pastry

• 500 g puff pastry, ready-made
• 1 medium egg, beaten, for brushing