A custard is an age old dessert made with eggs, sugar, and cream, cooked together into silky smooth bliss. The flavor of a custard, sweet and a little eggy, is rarely considered without the velvety texture that accompanies it. So much so that “custardy” is a reference point for other silky rich textures, like the prehistoric relic, the paw-paw, a fruit native to America often called a custard apple.
At its simplest, a custard is sweet cream thickened with egg, mostly the yolk but sometimes with the whole egg. Custard can be cooked over the stovetop to make stirred custards that are used as sauces like the famous creme Anglaise, or as the base for frozen custard, the richest of all ice creams. When the custard is baked in the oven, it creates the king of all desserts, the crackly caramel topped creme brulee, or its naked cousin, the pot de creme.
The egg yolk is the workhorse of custard, responsible alone for the increased viscosity that transforms sweet cream into thick sauces, spoonable puddings, and sliceable tarts. Inside each egg yolk are tiny bundled proteins, like little balls of tangled yarn. When heated, the proteins in the egg yolk begin to change their nature and unravel, or “denature.” Once denatured, the proteins in the egg yolk begin to overlap with each other, and everywhere these long strands touch, they form a cross-link. When enough of the proteins cross-link, they interrupt the flow of the water carried into our custard by the milk and cream. This interruption is called coagulation, meaning to change from a liquid into a semi-solid or solid state. Visually, you’d call it thickening. When the custard is stirred as it cooks, these cross links are partially broken as they are created, resulting in a custard that retains fluid properties. Simply put? A stirred custard flows when poured.
If we still-baked a custard in a dish (still-baking is a term pastry chefs use for not agitating it in any way), the denatured proteins cross link until they form a gel that looses its fluidity, becoming solid. These still-baked custards should be chilled before serving, allowing the butterfat in the custard to firm up, creating a silky custard we can spoon into our mouths. If we serve the sweet still-baked custard as is, it is considered a pot de creme, and if we sprinkle the top with sugar and use a torch to caramelize it, we have made a creme brulee. In Spain, a similar dessert is served, crema Catalan, the sugar caramelized by a disk of iron that has been heated in a wood fire.
Should you place the caramel in the baking dish before the custard is baked, the dessert is served inverted, released from it’s baking vessel, and called creme caramel, or in Spanish speaking parts of the world, flan.
Savory custards are also prized by chefs for their velvety texture, particularly on the breakfast table where eggs reign supreme. Flavored with herbs, or rich lobster, and often inclusive of cheese, savory baked custards are as delicious as their sweet brethren. Savory custards often hide inside pastry shells, where they go by the name quiche. Japanese chefs have long placed their savory custards in steamers, creating an even more delicate custard called chawanmushi.
Great care must be taken when cooking a custard, as the texture is entirely dependent on the point to which we cook the proteins in the eggs. If the eggs aren’t cooked enough, proteins don’t cross-link enough to disrupt the flow of water, and the custard is thin and runny. Should they be overcooked, the proteins in the eggs begin to coagulate tightly, forming small curds. These curds are wonderful for scrambled eggs, but are unwelcome in a custard.
A baked custard, contained in a heat proof baking dish called a ramekin or casuela, must be baked in a water bath. The surrounding water insulates the baking dish allowing a slow, even bake for the custard inside. Without the water bath, the baking dish will transfer too much heat from the oven to the custard, causing it to curdle against the edges. A stirred custard requires low heat and constant agitation with a wood spoon or rubber spatula. This ensures the heat that is introduced to the bottom of the pot is distributed evenly through out the custard as it cooks, and prevents the custard from curdling on the pot’s hot bottom and sides.
Because the proteins in egg yolks begin to coagulate at 155 degrees Fahrenheit, and become solid at 165 degrees, you can use a thermometer to monitor the temperature of a stirred custard. This ensures you never heat it past 165 degrees, and contemporary recipes often instruct you to bring your custards to this temperature. Traditionally, stirred custards are cooked to “nape.” This term describes the flow of the custard on the back of a spoon. To test for nape, dip a large spoon in the custard, then swipe with your finger across the back of it following the same vertical line as the handle, splitting the spoon into two hemispheres. Then, hold the spoon horizontally (as you normally would with spoon head right side up), to allow gravity to pull the custard downward. This old-fashioned trick allows you to easily see the viscosity of the thickening custard. Proper nape is thick and smooth, and barely moves when gravity pulls it down, like the flow of latex paint. Once this thickness is achieved, the custard is immediately poured from the pan into a bowl, which is placed in an ice bath and frequently stirred to stop the proteins from coagulating any further.
Baked custards require far less hands-on cooking, but do require you to check the texture of the baking custard frequently as it nears completion. A baked custard is finished when a gentle shake produces a wiggle that is like Jell-o. The center will be the last part of the custard to coagulate, so as you give your custards a little shake, watch the bullseye to see if it shimmies. If the outside jiggles, but the inside looks soupy, bake the custards for 10 more minutes. This checking-and-cooking stage can feel excruciatingly long at times. Once you open the oven door, and remove the foil cover from the water bath, the whole set-up needs to recover the lost heat before the custards begin to start cooking again. Over-checking can cause your custards to stop baking all together. Often, if many baked custards are cooking together, some will be done before others, and must be removed from the batch as the remainder finish cooking.
A water bath is easy to set up, simply fill a baking dish (preferably one with two-inch walls like a casserole dish) with the ramekins or custard dishes that hold your custard, then add enough hot water that the water level reaches half way up the sides of the ramekins. If you use cold water it will take your oven more time to warm the water bath, hot water is a better choice. Once the water is added, cover the whole pan with foil, and cut three-inch vents in it to allow steam to escape. I like to do this as close to the oven as possible, as moving the water filled pan can be a little tricky, and balance is necessary to keep any water from splashing into the custard filled ramekins.
It takes many tries to be able to pinpoint the exact moment when the egg yolks have cooked to its optimal state, and it is the true mark of an experienced pastry chef. The jiggle will solidify into the custard texture we all know and love after a few hours in a refrigerator. Luckily, custards are so delicious, you’ll find no complaints as you try and try again, narrowing down that moment of custardy perfection for yourself.
How to make proper creme brulee
The family of baked custards includes the king of desserts, creme brulee, with a crackly caramelized crust of sugar burned by the heat of a torch. Left naked, the custard is called pot de creme. Should you pour a tablespoon of just-made-caramelized sugar into the baking dish before you bake the custard, it can be inverted and served as a crème caramel, or flan.
Because these custards are baked in individual heat proof baking dishes called a ramekin, they must be baked in a water bath. The surrounding water insulates the ramekin allowing a slow, even bake for the custard inside. Without the water bath, the baking dish will become too hot from the heat of the oven, causing the custard to curdle at the edges.
- 150 g egg yolks
- 100 g sugar
- 1 vanilla bean
- 500 g cream
- 100 g whole milk
- Preheat your oven to 300 degrees Fahrenheit.
- Place the sugar in a medium-sized bowl. Split the vanilla bean lengthwise and scrape the seeds into the sugar, reserving the pot for another use.
- Use your fingers to rub the vanilla seeds into the sugar. The granulated sugar will help break apart the goo that holds all the seeds together, and as you rub you will disperse all these seeds into the sugar evenly. Sift the vanilla sugar into a bowl and add the egg yolks, and whisk until the two are evenly combined.
- Place the cream and milk in a pot and cook over medium high heat until it comes to a simmer. Carefully add the cream and milk to the egg yolks, and whisk until evenly combined. Let the custard sit for 30 minutes, allowing any foam to rise to the top of the container to be spooned away.
- Divide the custard between four 6 oz. baking vessels, filling them 3/4 of the way full (each should have a little over 200 grams).
- Place the custard cups in an ovenproof baking pan, such as a 9-by-12 inch cake pan. Add the hottest tap water you can get from your faucet to the baking pan until the water level comes half way up the sides of the custard cups. Cover the baking pan with foil, and cut six vents in the foil to allow steam to escape. (I recommend preparing this on your stove top or the surface closest to your oven to avoid splashing water into the custards when you transport into the oven.)
- Bake the custards for 40 minutes, untouched. After 40 minutes, open your oven pull the rack forward. Lift the foil carefully, avoiding the steam that will escape (it gives nasty burns). To check for doneness, tap one of the custard cups to asses the jiggle of the baked custard. If it ripples, the custard is not yet set, return the foil cap, shut the oven door, and bake another 15 minutes before checking again.
- If the custard jiggles to the center like barely set Jell-o, get that pan out of the oven! Your custards are baked to perfection and need to be removed from the water bath to stop cooking. I like to use a pair of garden gloves to carefully lift the hot custard cups from the water bath, and set them on a wire rack. You can use a spatula, or any other method that keeps your fingers from burning, and the custards from tipping to the side, thus tearing the extremely delicate, barely set custard. Let the custards cool at room temperature for about 10 minutes, then transfer them to the refrigerator to set for 4 hours minimum.
- If the custards don’t have any bounce left when you tap them, they are over cooked, get them out of the oven and onto a wire cooling rack, pronto. There is the likelyhood that these custards will have tiny bubbles along the exterior, a sign that they were overcooked in the oven. Chill them and eat them anyways, they might not win a ribbon at a french county fair, but they will be darn tasty.
- Once your baked custards are set, you can serve them as pot du creme, with a simple topping of crushed raspberries, a little caramel sauce, or nothing at all. Should you sprinkle the custards with granulated sugar, then use a blowtorch to burn that sugar into caramel brown submission, you will have the king of all desserts on your hands: the creme brulee.
Coming this week: Dana Cree’s recipes for creme Anglaise, flan, and frozen custard.