Instructions
Combine 2 tablespoons of plain flour and 2 tablespoons of icing sugar in a small bowl. Sprinkle this mixture onto a clean, dry work surface. Place the 375g puff pastry on the floured surface. Use a rolling pin to roll the pastry into a rectangle. It should measure about 45 cm by 30 cm. Starting from one long side, tightly roll the pastry into a log. Then cut the log in half.
Use a sharp knife. Cut each pastry log half into 12 pieces, for a total of 24 pieces. Each piece should be 1 to 2 cm thick.
Lightly flour your work surface again. Take one pastry piece. Use a rolling pin to gently flatten it into a round disc. The disc should be large enough to line one cup of a 12-hole non-stick fairy cake tin. Repeat for all 24 pastry pieces. Place each flattened pastry disc into a cup of the fairy cake tin. Gently press the pastry up the sides and into the bottom. This forms a thin pastry case. Place the filled tins in the refrigerator to chill.
Preheat your oven now. Set it to 220 degrees Celsius (425 degrees Fahrenheit). If using a fan oven, set it to 200 degrees Celsius (390 degrees Fahrenheit) or Gas Mark 7. In a small saucepan, combine 250g caster sugar, 200ml water, 2 strips of lemon zest, and 1 cinnamon stick. Bring this mixture to a boil over medium heat. Reduce the heat. Simmer until the mixture thickens slightly and becomes syrupy. Remove the saucepan from the heat. Let the syrup cool completely. Once cooled, remove and discard the cinnamon stick and lemon zest strips.
In a large saucepan, whisk together 2 whole eggs, 4 egg yolks, and 50g cornflour. Whisk until the mixture is smooth and lump-free. Set this saucepan aside. In a separate saucepan, heat 500ml whole milk. Add the seeds scraped from 1 vanilla pod, if using. Heat until small bubbles appear around the edges. Do not let the milk boil vigorously; it should be just below boiling point.
Slowly pour the hot milk mixture into the egg and cornflour mixture in the large saucepan. Whisk continuously as you pour. Place this large saucepan over low heat. Continue whisking constantly until the custard mixture thickens. Pour the cooled sugar syrup from Step 4 into the thickened custard. Whisk until the custard mixture becomes slightly thicker.
Place a fine-mesh sieve over a clean bowl. Carefully pour the custard mixture through the sieve. This removes any lumps or solids. Retrieve the chilled pastry cases from the refrigerator. Carefully spoon or pour the sieved custard into each pastry case. Fill them almost to the top.
Bake the tarts in the preheated oven for 15 minutes. The pastry should turn golden brown. The custard tops should look darkened. Remove the tins from the oven. Let the tarts cool completely in the tins. Place them on a wire rack to cool.
Once the tarts are completely cool, carefully remove them from the tins. Before serving, you may sift icing sugar and ground cinnamon over the top of each tart. This is optional.