Make the pastry first. Preheat oven to 410°F (210°C).

Place all ingredients for pastry except flour in a medium-sized, oven-proof bowl.

Prepare your tart tins by placing them on a baking sheet, ready for the pastry once it comes out of the oven.

Remove bowl from the oven with oven mitts, set on heat-proof surface, and sprinkle flour into the bowl. Be careful of the hot butter mixture splashing. With oven mitts still on, stir with a wooden spoon until well blended.

Divide into four equal parts and place into waiting tart tins (or leave as one ball if you are using one larger tin).

While the pastry is cooling in the tart pans, but before being baked, make the pastry cream. In a medium sized bowl, combine the sugar, corn starch and egg, and whisk thoroughly.

Pour the cup of milk into a small saucepan, and heat to scalding over medium heat.

When small bubbles start to form on the bottom of the pan, and the milk starts to steam, pour about 1/3 of the milk in a fine stream into the sugar/corn starch/egg mixture, whisking all the time.

Then pour this mixture back into the pan, place back over heat, and continue to whisk constantly, until the pastry cream bubbles and starts to thicken. If it seems like it's getting too hot, lift the pan from the burner and keep whisking, placing back down as needed to keep hot.

Once thickened to the consistency of pudding, remove from the heat, and immediately scrape into a medium sized bowl. Set aside, and whisk every couple of minutes to help it cool down more quickly, and to avoid a skin forming on top of the pastry cream.

While the pastry cream is cooling, press the tart dough into the tins, prick the bottom of the tarts with a fork, and place in oven to bake. Bake for about 15 minutes, or until just starting to turn golden. Once baked, remove and place on a cooling rack.

Allow tart shells to cool completely before filling each tart with cooled pastry cream, and topping with sliced strawberries. Serve immediately. If you aren't eating them all at once, leave the pastry cream and strawberries separate from the tarts you are saving for later. The pastry cream can be kept in the fridge in a sealed container for a couple of days, the tart shells can be kept at room temperature.