Place the cornstarch and sugar into a large saucepan and mix.

Slowly add in the milk while whisking vigorously so that no lumps form.

Stir in vanilla and yellow food coloring.

Place the saucepan on medium low heat and bring the mixture to a boil, while constantly whisking. Within 6-8 minutes you will notice, as you whisk, the mixture becomes thicker.

At this point, remove the pot from the stove but continue to whisk for at least another minute until the mixture is thick and creamy.

To prevent a skin from forming, cover the custard with plastic wrap, making sure that the plastic is in contact with the surface of the custard.

Leave to cool at room temperature for at least 45 - 60 minutes.

Unroll one sheet onto a lightly floured surface. Preheat the oven to 400 °F (200 °C) (180°C fan assisted oven)

Line a baking sheet with parchment paper

On a lightly floured surface, roll out the pastry to about 1/16 inch (2mm) thickness. Use a sharp knife or pizza cutter to cut 1x3 inch (3x8 cm) rectangles.

Place the rectangles about 2 inches (5cm) apart on the lined baking sheet. Pierce each rectangle well with a fork.

To ensure your pastry doesn't rise too much, weigh it down with a metal cooling rack that you have sprayed with non-stick cooking spray. If you really want to put extra weight on your pastry, you can put any metal or glass baking pan filled with water (or baking beans) on top of the cooling rack.

Bake for 20 to 25 minutes until the pastry is golden brown and crisp.

Remove the baking sheet from the oven and lift the cooling rack off the pastry.

Make sure to use oven mitts to avoid burning your hands, because the cooling rack will also be hot.

If the pastry is stuck to the cooling rack, gently slide a butter knife or a spatula between the pastry and the cooling rack to help loosen it.

Leave the baked pastry to cool completely before filling with the cooled custard.

If the custard has set while cooling, whisk it well to break up any lumps and get it to a creamy consistency. If you still see some lumps, don't worry - they will either disappear or be hardly noticeable once the custard is piped onto the pastry.

Pipe a double layer of custard onto one of the pastry pieces. Place a second pastry piece on top, repeating the process with the remaining pastries and custard.

To finish, top with sifted powdered sugar. They can now be served immediately or refrigerated for an hour before serving.

Can be refrigerated for up to 2 days in an airtight container. However, it is important to keep in mind that the longer the pastry is stored, the more likely it is to absorb some liquid from the custard, leading to a loss of crispness.