In a medium-sized bowl, whisk together the eggs, sugar, salt and cornflour (US: cornstarch) until the mixture is smooth.

In a medium-sized saucepan on medium-high heat, warm the cream and vanilla (if using) until it comes to a gentle simmer.

Remove the pan from the heat.

Slowly pour about half of the warm cream into the egg mixture, whisking as you do so.

Then pour the egg mixture into the pan with the rest of the cream.

Return the pan to the stove on medium-high heat.

Continue whisking until the custard starts to thicken substantially. It should be the consistency of a thick yoghurt, but it will thicken more as it cools.

Place a fine sieve over a large bowl.

Transfer the custard to the sieve.

Use a large spoon or spatula to push the custard through the sieve. This step will remove any lumps and overcooked egg from the custard, and which will give you a silky smooth custard.

Cover the surface of the custard with a layer of plastic wrap, which will prevent a skin from forming on the custard as it cools.

Place the custard in the fridge to cool and firm up, at least 2 hours or overnight.

Measure all of the dry ingredients into a large mixing bowl or the bowl of an electric stand-mixer (if using).

Measure the warm water and oil into a measuring jug. The water needs to be a bit more than lukewarm to help activate the yeast, but it shouldn't be boiling hot.

Using the dough hook on medium speed, mixing the liquid ingredients into the dry ingredients. Depending on the type of flour which you have used, you might need more or less liquid that than stated in the recipe.

Once you have a sticky dough, continue kneading the dough on medium speed until it becomes soft and smooth to touch. This should take about 10 minutes using the stand-mixer on medium speed, or about 5 minutes by hand.

Once the dough is soft and smooth, I recommend kneading it by hand for a few more minutes on the kitchen benchtop.

Place the ball of dough back into the (clean) mixing bowl.

Cover the bowl with some cling film or a re-usable bowl cover.

Place the bowl somewhere warm for about 60 to 90 minutes for the dough to rise and double in size.

Place the dough onto a clean surface.

Gently shape the dough into a large round ball.

Use a large knife to cut the dough in half, then into quarters, and then cut each quarter into 3 pieces to produce 12 pieces of dough in total.

Stretch and roll each piece of dough into a small, round ball.

Take a piece of dough and use a small rolling pin to roll it into a flat, round shape.

Then use the rolling pin to thin and stretch out the edges, so that the middle of the dough is slightly thicker than the edges. The dough should measure approx. 10 cm/4 inches in diameter.

Place the rolled out dough into your left hand (if you are right-handed).

Place a tablespoon of the custard filling into the centre of the dough. I use an ice-cream scoop for this task.

Use the thumb and index finger on your right hand to crimp the edges of the dough together.

Pinch the crimped edges together, and twist slightly to seal the buns.

Place the prepared bun onto a large baking sheet lined with baking paper, with the seal facing down.

Repeat the above steps for the remaining buns.

Once all of the buns have been prepared, cover them with a clean, damp tea towel. Place the tray somewhere warm for about 30-45 minutes, or until the buns are slightly puffed.

Meanwhile, prepare the steamer on the stove (see Kitchen Notes below).

Steam the buns in batches for 10 minutes.

Serve the buns immediately.