The Custard Continuum
Last time, we explored the role of starches and gelatin as thickening agents, primarily in the context of dessert. This week, we will focus on the egg. We’ve already talked about eggs in some detail in our Eggs 101 series. This time though, the focus will be on its role in custard making. At the end, we will still stick to a basic Dairy + Sugar + Egg + Vanilla formula and create three similar yet very different desserts.
The science behind the egg is very similar to that of starch. Agitating the egg by mechanical force or heat breaks open the strands of egg protein which then interlink with each other, producing a cohesive complex. And this is why a liquid egg sets solid on being heated. If there is other stuff added to the egg mix, it gets trapped in the mesh, causing the mixture to set.
This property of the egg is the basis of the basic egg custard. Store-bought custard powders usually employ the power of cornstarch to obtain a set. The classic French custard or crème anglaise (literally “English cream”) however, harnesses the power of the egg. All it takes is some eggs, dairy, sugar and flavoring.
An important consideration to be made at this stage is the amount of fat desired in the end-product. This is a trade-off between protein and fat; more protein leads to a firmer set, more fat produces a softer but richer product. If a firm set isn’t a concern, as in a custard sauce like crème anglaise, it is a safe bet to go for a fatty mixture, which means ditching the whites entirely.
Milk is taken in a saucepan and heated with a scraped vanilla bean, pod and all. Egg yolks are whisked vigorously with sugar until the sugar dissolves and the mixture turns fluffy and light in colour, what the French would call a sabayon, whose Italian cousin, the zabaglione, spiked with marsala, is often had as a dessert on its own, or forms the starting point of a classic tiramisu.
Adding the sabayon directly to hot milk however, may cause it to scramble immediately, creating a lumpy, eggy mixture. This is where tempering comes into play. Small amounts of the hot dairy is added to the eggs and whisking vigorously, to prevent scrambling. This now warmed egg mix is added back to the rest of the milk, and cooked till the mixture thickens and coats the back of a spoon.
One of my chef friends suggests that as long as the milk isn’t too hot, the entire tempering ritual can be bypassed. For a beginner though, this shortcut may easily backfire, and it is best to take it slow with the tempering strategy. The crème anglaise is one of the most basic dessert sauces, great with a soufflé or even fresh fruit. It is an integral component of the classic Île Flottante or Floating Island.
The crème anglaise forms the base for Bavarian cream and even ice cream. And finally, it forms the base for three classic French desserts, which are variations on the theme of oven baked custards. This is very similar to the steamed “pudding” my mother used to make in a pressure cooker. The French pastry chef however, takes things a few steps further.
A set custard needs to be thicker than a pourable custard sauce, so the proportion of egg yolks in our first dessert has to be significantly higher than a crème anglaise. More yolk translates to more protein, hence a firmer set. But it also means more fat. Add to that heavy cream instead of milk, you’ve got the beginnings of a rich, indulgent crème brûlée.
To make one, all you need to do is whisk egg yolks, sugar and vanilla together, then add to it boiled and cooled down heavy cream, a little at a time, The mix is poured into ramekins and baked. To ensure that the mixture cooks slowly, a water bath is employed, which ensures that the oven temperature never rises above 100 degrees Celsius.
When done, they are chilled completely before granulated sugar is sprinkled on top and burnt with a blowtorch until it melts and cools into a crisp, glassy crust, specked with black. Play around with the flavours: orange zest, cardamom, coffee; the world is your playground. And as I’ve already described in a previous article (check it out here), the crème brûlée is the ultimate dish of contrasts.
The second baked custard is probably the least popular of the three, although it is equally amazing. The pot au crème ditches the gimmick of the brûlée and is simply a baked custard. And since we have no crisp sugary crust to counteract the richness of the custard as in a crème brûlée, it is wise to use a mixture of cream and milk for a pot au crème.
You could make a simple vanilla pot au crème, which is essentially the crème brûlée minus the brûlée. Or you could go the extra mile and make a chocolate or salted caramel pot au crème. The latter still sticks to the four ingredient limit we agreed to at the beginning, although you’re gonna need a touch of salt to make the caramel sing.
Our third dessert needs to have a firmer texture than the other two, since it is traditionally served out of the ramekin. And that is why the mixture for a crème caramel or flan uses whole eggs rather than just yolks. The protein in the egg whites allows the custard to be firm enough to hold its own out of the ramekin. It is common practice, however, to add a few extra yolks into the mix for added richness.
It’s the same drill all over again, with one crucial difference. The ramekins are prepped first with a layer of caramel at the bottom, before adding the custard mix. After it is baked, the ramekin is upturned, creating a baked custard with an amber top surrounded by a delicious pool of caramel sauce. Texturally, this comes the closest to the Indian pressure cooker pudding. The caramel takes it to the next level.
Custard desserts are a great lesson in elegant simplicity. With just four ingredients and the right technique, we can create an astonishing array of desserts that are bound to impress and please in equal measure. Join us next time as we explore two other desserts which employ some rather mysterious and unconventional methods of thickening.