The filling in this tart is everything.
The tart is basic—a great crust, velvety lemon cream; and profoundly satisfying. It is also profoundly playaroundable.
You can add a fruit topping (circlets of fresh raspberries are spectacular with this tart) or a layer of fruit at the bottom; you can finish the tart with meringue, or you can serve it with anything from whipped cream to raspberry coulis.
1 9-inch tart shell made with Sweet Tart Dough, Sweet Tart Dough with Nuts or Spiced Tart Dough, fully baked and cooled.
- 1 cup sugar
- Finely grated zest of 3 lemons
- 4 large eggs
- 1/2 cup fresh lemon juice (from 4-5 lemons)
- 2 sticks plus 5 tablespoons (10-1/2 ounces) unsalted butter, cut into tablespoon-size pieces, at room temperature
Getting Ready: Have an instant-read thermometer, a strainer and a blender (first choice) or food processor at hand. Bring a few inches of water to a simmer in a saucepan.
Put the sugar and zest in a large heatproof bowl that can be set over the pan of simmering water. Off the heat, rub the sugar and zest together between your fingers until the sugar is moist, grainy and very aromatic. Whisk in the eggs, followed by the lemon juice.
Set the bowl over the pan, and start stirring with the whisk as soon as the mixture feels tepid to the touch.
Cook the lemon cream until it reaches 180 degrees F.
As you whisk—you must whisk constantly to keep the eggs from scrambling—you’ll see that the cream will start out light and foamy, then the bubbles will get bigger, and then, as it gets closer to 180 degrees F, it will start to thicken and the whisk will leave tracks.
Heads up at this point—the tracks mean the cream is almost ready. Don’t stop whisking or checking the temperature, and have patience—depending on how much heat you’re giving the cream, getting to temp can take as long as 10 minutes.
As soon as it reaches 180 degrees F, remove the cream from the heat and strain it into the container of the blender (or food processor); discard the zest.
Let the cream stand, stirring occasionally, until it cools to 140 degrees F, about 10 minutes.
Turn the blender to high (or turn on the processor) and, with the machine going, add the butter about 5 pieces at a time. Scrape down the sides of the container as needed as you incorporate the butter.
Once the butter is in, keep the machine going—to get the perfect light, airy texture of lemon-cream dreams, you must continue to blend the cream for another 3 minutes.
If your machine protests and gets a bit too hot, work in 1-minute intervals, giving the machine a little rest between beats.
Pour the cream into a container, press a piece of plastic wrap against the surface to create an airtight seal and refrigerate for at least 4 hours or overnight.
(The cream will keep in the fridge for 4 days and, or tightly sealed, in the freezer for up to 2 months; thaw it overnight in the refrigerator.)
When you are ready to assemble the tart, just whisk the cream to loosen it and spoon it into the tart shell. Serve the tart, or refrigerate ‘until needed.
Serving: It’s a particular pleasure to have this tart when the cream is cold and the crust is at room temperature. A raspberry or other fruit coulis is nice, but not necessary; so is a little crème fraîche.
I know it sounds odd to offer something as rich as crème fraîche with a tart like this, but it works because the lemon cream is so light and so intensely citric, it doesn’t taste or feel rich.
Storing: While you can make the lemon cream ahead, once the tart is constructed, it’s best to eat it the day it is made.
Of Lemon Cream
At first glance, you would think that the lemon cream is just another version of lemon curd—the ingredients are almost identical. What’s different is how they are treated, and it makes an enormous difference in the taste and texture.
In a curd, the eggs, lemon juice, sugar and butter are cooked together until they thicken. The result is silky, lemony and, above all, unmistakably rich and buttery.
The mixture is then poured into a blender and allowed to cool for a few minutes. Then the butter is added, in pieces, and the cream is whipped around for a few minutes.
Here’s the genius—instead of melting as it does in curd, the butter emulsifies (just as oil does in mayonnaise), so that the resulting texture is velvety and deceptively light. It is a stroke of culinary magic.
Like curd, lemon cream is a utility player. It can be spread on toast, used as a filling for cakes and pies, spooned over fruit desserts or just eaten off the spoon when no one is peeking.