The science behind perfect Mexican flan

Mexican flan, a distant cousin of the crème brûlée, is a smooth, decadent custard-based dessert. Next time you do Mexican night at home, this will be the perfect finishing touch to your fiesta — it’s not as tricky to make as you might think. Here’s how it’s done.

Creme caramel

The science of perfect flan lies in the fact that, unlike most custard-based dishes, it contains both egg yolks and egg whites. Egg yolks are made up of fat, protein and about 50% water. The fat in the yolk gives desserts like crème brûlée, crème caramel and flan their creamy and smooth texture.

However, if we tried to make flan with yolks alone it would not set, because the mixture wouldn’t contain enough protein and water. This is why we need the egg whites. Egg whites are made up of 80% water. They contain no fat (as you may remember from our meringue making adventure) and slightly more protein than egg yolks, giving them wonderful thickening power. Adding egg whites to the flan ensures that it will set beautifully, so we can turn our little custard beauties out of their moulds to serve.

Keeping all of that in mind, let’s start making our flan.


For the caramel sauce

150g sugar
6 tbsp water

For the custard

4 large eggs
1/2 tsp vanilla extract
30g caster sugar
600ml full cream milk

You will also need:

6 x 200ml pudding moulds
A roasting dish for baking
A stainless steel saucepan for making the caramel


1. Preheat the oven to 150℃.

TIP: Heat the pudding moulds in the oven while you’re make the caramel. This will make it easier to spread the caramel and also prevent crystallisation.

2. Heat the sugar and water over medium heat, stirring (with a wooden spoon) until all the sugar has dissolved. Boil without stirring until the mixture turns a light copper colour.

TIP: At this point, immediately put the bottom of the pan into a sink full of lukewarm water. This will stop the caramelisation and prevent burning.

3. Quickly pour the caramel into the bottom of the pudding moulds and set aside to cool at room temperature.

Caramelized sugar

4. Once the caramel has hardened, butter the sides of the pudding moulds so the pudding doesn’t stick.
5. Gently warm the milk in a saucepan over the stove. It must be warm, but not boiling or too hot to dip your finger in. (The temperature here is key, so be careful).
6. Whisk the eggs, vanilla and sugar together in a bowl.
7. Once the milk is warm, pour it into the egg mixture and whisk until smooth. Then pour your mixture into the prepared moulds.

Custard mixture in pudding moulds

8. Place the moulds in a roasting dish and carefully fill the dish halfway with boiling water.
9. Bake the flans for about 20 minutes, or until a knife inserted into the center comes out clean.

TIP: They will still be quite ‘wobbly’, but don’t be tempted to leave them in for too long as this may result in sweet scrambled egg.

creme caramels out from the oven

10. Cool the flans in the fridge for at least an hour, preferably overnight. This will allow the custard to absorb the caramel flavour, and for the caramel to steal water from the custard and soften.
11. Gently loosen the sides of the custard with a palette knife, and turn upside down onto a dessert plate to serve.

It’s as easy as that — your decadent, creamy treats are ready to be shared and enjoyed.

Creme caramel with final dressing

Flan is a great choice for summer days and for when you need to make something ahead.