1tablespoonfirmly packed finely grated lemon zest (from about 2 large lemons)
1 ½cups(340 g) organic granulated sugar (or 1 ¼ cups / 275 g for extra tangy bars)
1/8teaspoonfine sea salt
2large egg yolks
1cup(235 ml) strained lemon juice (from about 6 large lemons)
Optional garnishes: heavy cream and crème fraiche whipped to firm peaks, bee pollen for sprinkling
Prepare, parbake, and press the tart crust as directed.
Lower the oven temperature to 325ºF.
Place the butter and lemon zest in a heatproof bowl. Place a mesh strainer over the bowl and set aside.
In a medium, heavy-bottomed saucepan, whisk together the sugar, salt, eggs, and egg yolks to combine. Gradually whisk in the lemon juice.
Place the pot over medium-low heat and cook, stirring constantly with a heatproof silicone spatula, until the mixture thickens slightly and reaches 160-165ºF on an instant-read thermometer, 5–10 minutes. As you stir, be sure to scrape the entire bottom and corners of the pan, so that the mixture heats as evenly as possible. It will start out thick and cloudy from the undissolved sugar, then will turn thin and translucent, and finally begin to thicken and turn cloudy again as the eggs cook. Lower the heat to very low as it gets closer to being done. If the mixture starts to curdle or bubble, immediately remove it from the heat and proceed to the next step.
Immediately pour the curd through the strainer and into the bowl of butter to stop the cooking. Whisk to incorporate the butter and lemon zest, making sure there are no clumps of lemon zest.
Pour the cooked curd over the baked and pressed down crust. If you have extra curd, you can save it in the refrigerator for up to 1 week. It's delicious swirled into yogurt or slathered on toast or biscuits.
Bake the tart at 325ºF (don’t forget to lower the oven temp!) until the sides are barely puffed and the center wobbles like firm Jell-O when you give it a gentle shake, 15–25 minutes. It should not be wet or watery looking (underbaked), nor should it be puffed in the center or cracking (overbaked). Remove the tart from the oven and let cool to room temperature for about an hour, then chill until firm, 3-4 hours or overnight.
When the tart is cold, loosen and remove the sides of the tart crust and slide it onto a cutting board. Cut into wedges with a large, sharp chef's knife. For the cleanest cuts, dip the knife in very hot water and wipe the blade clean between cuts.
Just before serving, dust the tart with a bit of powdered sugar or garnish with lemon wheels and/or whipped crème fraîche if you like.
The tart keeps well, refrigerated, for up to 3 days, though the crust is the crispest within the first 1–2 days.
Gluten-Free Lemon Bars:No tart pan? No problem! Bake the same recipes as lemon bars following the recipe here. Meyer Lemon Tart:Use the smaller amount of sugar and make the tart with Meyer lemon zest and juice.Make-Ahead:This lemon tart is best within two days of baking when the crust is crisp. It keeps well in the fridge for up to 4 days. I don't recommend freezing the bars once baked since it might make the curd grainy or watery. However, you can make the crust ahead and freeze it – baked or unbaked – until you're ready for tart. You can prepare the lemon zest and juice a day or two ahead and refrigerate them until you're ready to bake. You can also cook the curd ahead of time, chill it for up to 3 days, and soften it in a bain marie before pouring it into the baked crust and proceeding with the recipe. Nutrition values are for 1 of 10 servings of the filling only.