How Zachary Golper Makes Bien Cuit's Kaffir Lime Eclairs

These days – especially since Golper has been busy co-authoring and now promoting his cookbook, Bien Cuit: The Art of Good Bread – pastry production is the responsibility of Justin Binnie, the bakery’s sous chef. He’s the one who creates the eclair flavors, but whether he makes them or Golper makes them, the result is the same: a slightly crisp, never soggy shell; a delicate, silky cream filling; and pretty, intricate adornments.

One of the eclairs currently on the menu is a kaffir lime and coconut number, which looks like the creation of a woodland fairy and tastes like a tropical vacation. The kaffir lime filling is pertly sour. The coconut cream on top is richer than it looks. And the toppings of finger lime, coquito nut, and sponge cake add texture and the perfume of basil.

To start, Golper makes the choux pastry – the shell of the eclair. Binnie has experimented with using different flours like buckwheat here, and he also makes a chocolate choux, but this one is made with a standard white bread flour, which Golper likes for its unfailing consistency.

Choux recipes never veer far from the one the French have been making for centuries. It can’t if it’s going to achieve the right puff, and the right crisp-but-tender texture. Golper starts by combining milk, water, and chunks of butter in a pot and bringing it to a boil. He explains that, though some add flour right away, he likes to let it boil for a few seconds. American butter has a higher water content than French, and he wants to boil that off.

Once he’s dumped in the flour (and a little sugar), Golper starts stirring. He stirs steadily but not vigorously, enough to keep a film from developing on the bottom of the pan. First the paste "takes on a texture like mashed potatoes." Then Golper watches for it "to take on a sheen," which means that the starch in the flour has been fully saturated with moisture. That sheen, Golper says, is something you only recognizable with experience.

When the paste is glistening, Golper transfers it to a stand mixer. Steam billows out of the bowl as he begins beating it, mostly to cool the paste down faster. He’ll add eggs next, and if the mixture is too hot, those eggs will scramble immediately.

When the paste stops steaming, and the bowl isn’t so hot it hurts to touch, the eggs go in one by one, with the mixer on low. After each egg goes in, "the batter usually completely falls apart," Golper says. Then it comes back together, "and as soon as it does, add the next egg." Add too many eggs too quickly, and they’re likely to go flying out of the bowl.

Always before adding the last egg, Golper tests the consistency of the batter. He pinches a little between two fingers, then pulls them apart smoothly. If the batter stretches between them without breaking, it’s right. If the ribbon breaks, he adds that last egg.

Golper scoops the batter into a piping bag fitted with a star-shaped tip. His baking sheet is lined with two pieces of parchment paper. The bottom one is battered and used, and has carefully measured eclair-length drawn at angles across it. The top sheet is clean and crisp and translucent enough that the lines underneath show through. It takes a steady hand and even pressure to pipe a straight eclair, and Golper draws the piping tip over the parchment slowly but without pause. He pulls up sharply to break the flow, leaving behind a little peak that he’ll later flatten with an egg-white-moistened fingertip.

These yolk-yellow logs of choux take a long time to bake for such a little pastry: a whole hour. They start at a high temperature so that they puff tall and then set that way, leaving a hollow inside. Then after half an hour the temperature is lowered, so that the insides can cook through without the outsides burning.

Meanwhile, Golper makes the kaffir lime cremeux that goes inside these eclairs. Into a large bowl go kaffir lime juice, sugar, and about as many egg yolks, by weight, as whole eggs, plus the zest of a couple kaffirs and the seeds of two whole vanilla beans. Golper whisks all this steadily over a pot of a little simmering water. He says he often just makes a cremeux over direct heat, but an egg-heavy custard like this can overcook and curdle in a flash, and the gentle heat of the double boiler makes that easier to avoid.

When the mixture has visibly thickened – the common cookbook description is that it "coats the back of a spoon," but Golper just watches the surface as he stirs – the bowl comes off the heat and Golper stirs in gelatin. Like in most professional kitchens, the gelatin is in sheets, not powder, and has to be soaked in cold water first.

Then he stirs in chunks of butter. It’s extremely important, Golper says, to keep stirring as the butter melts. Some pastry chefs in big busy kitchens drop the butter in and leave it to melt before stirring the whole thing together, but Golper thinks this makes for an inferior texture: more grainy, less silky.

The butter melts and disappears into the cremeux quickly, and Golper strains it through a chinois to get out any stray egg lumps. Now it has to cool for a little while before it can be piped into the eclair shells.

When it’s time, Golper loads the cremeux into a pastry bag, this one with a small round tip. He pokes two holes in the top of the pastry, one at either end. Filling from both ends ensures the entire thing gets filled evenly. The holes go on the top so that they’ll be hidden by the coconut cream when the eclair is finished. Golper squeezes the cremeux into the pastry gently, so that it fills the inner cavity without bursting out everywhere. He can tell when the eclair is full by its weight, and by the bit of cremeux that starts to squirt out around the piping tip. Occasionally an eclair springs a leak on the side, but Golper just swipes away the dribbles and the rest stays inside.

Finally, Golper pulls out his battery of toppings. There’s a thick, mousse-like coconut cream, made by combining coconut milk, sugar, and gelatin with milk that has been infused overnight with toasted coconut (which was strained out). Once this has chilled overnight to the consistency of soft Jello, it’s whisked into something that looks like whipped cream but is actually much thicker, and much more stable. This gets spread over the top in dollops, carefully caressed to look neither planned nor sloppy.

Next, the pastries get a dusting of kaffir lime zest, then Golper breaks off rough chunks from a spongy, basil-flavored green cake in a paper cup. This cake, he explains, "is a little space-agey": it was made in the microwave. It’s a classic sponge cake recipe, made with olive oil that’s had fresh basil blended in. This gets squirted out of a whipped cream gun into the paper cup, which is then microwaved into a super spongy, moist and tender cake. Doing it this way, Golper explains, not only makes a cake with no crust (which can’t be used on the eclairs) but also keeps the color of the basil a vibrant green and the flavor just like the fresh leaves.

Finally, the eclairs get a few slices of coquito nuts, which are – in look and flavor – essentially miniature coconuts. The eclairs also get a scattering of the tiny, luminous pearls squeezed out of a finger lime, which are carefully placed on top with tweezers.