How to make Lemon Curd (for Lemon Tartlets)

Sweet, crumbly dough filled with creamy lemon curd… Lemon desserts are such a bright and colorful addition to a dinner party, aren’t they? I mean, sure, chocolate desserts will always have a special place in my heart. But having the occasional lemon tart can be so refreshing!

Lemon curd can be used in so many ways. Fill your cupcakes with it for a delicious fruity center. Or spread it between your cake layers for an impressive dessert. You can use lemon curd in practically any dessert you can think of: cookies, cheesecakes, ice-cream… And if you happen to have some left-over, then just grab a spoon and dig in!

But my favorite way of using it is in tarts. Every Christmas, my aunt would make lemon tarts and they were one of the first things to disappear. Well, maybe my brother and I had a “small” role to play in this…cough cough…

We already covered how to make pâte sucrée and next time we will be talking about pâte sablée. You can use whichever dough you prefer or that you have on hand. Now all that’s left to make is the lemon curd. And it is actually so easy and so quick to make!

Bakeware Used

Before we dive into the ingredients needed to make a lemon curd, let’s talk about the type of pans, bowls, etc. that you should be using, or rather shouldn’t be.

Using the wrong type of bakeware when making lemon curd can ruin your dessert and give off a metallic taste and sometimes discolor the curd. Make sure to use nonreactive pans to prevent the acidity of the lemons from reacting with the metallic surfaces.

Nonreactive bakeware includes: stainless steel, glass, ceramic and those that have a nonstick or enameled surface.

Reactive bakeware that should be avoided are those made with cast iron, aluminum, copper.

Ingredients

Eggs

It is possible to use whole eggs, egg yolks or even a combination. I have personally always used whole eggs with success and I find it simpler than to have to separate eggs. Using whole eggs will produce a lighter curd than if you use egg yolks.

If you want a richer lemon curd and deeper color, you could replace a part (or all of the eggs) with egg yolk. It might be useful for you to know that an egg yolk weighs about 20 g while the whole egg weighs about 50 g. So to replace a whole egg, you would need slightly more than 2 egg yolks, although you can probably just round it up to 2 egg yolks.

Aside from the flavor added (especially from the yolks), the eggs contribute to the thickening of the lemon curd.

Sugar

From the recipes I’ve seen online, granulated sugar seems to be the most popular choice. You can find however several recipes made with honey, although I personally haven’t tested any yet.

The sugar will add sweetness and you can use more or less depending on how tangy or sweet you want your lemon curd to be.

The sugar will also play a role in protecting the eggs. The acid from the lemon juice will have a tendency to coagulate the eggs. To prevent this, eggs are usually mixed with the sugar before adding the lemon juice.

Lemon juice

It’s best to grate and squeeze lemons just before preparing your lemon curd. Unless you really can’t use fresh lemons, it’s better to avoid bottled lemon juice. The complex flavors found in citrus fruits are quickly lost when a lemon is squeezed.

Lemon Zest

Some recipes will include lemon zest, others won’t. It is really up to you, whether or not you’d like to add some. There are a few things to keep in mind though.

1. Use a microplane: You can of course use other types of graters but a microplane zester will make your job much easier and you won’t end up with large pieces of zest in your curd! Especially if you are too lazy to strain the lemon curd like I am!
2. Grate only the colored, outer layer: You don’t want to get the white part into your cream. It will taste bitter and ruin your lemon curd.
3. Add the zest to the sugar: Rub the zest and the sugar together (you can use your fingers) and let the flavors develop for 10 minutes.

I’m normally a huge fan of lemon zest and will go overboard with it. But I tried a recipe taught in french pastry schools that I found on the blog encore un gâteau without zest and the taste is already perfect. I thought it might simplify things so I kept the recipe as is. Feel free to add some to the recipe.

Want the zest flavor and a silky texture? No problem, add the zest then strain the cooked lemon curd through a fine mesh sieve.

Using other citrus fruits

If you want to change the flavor profile of the recipe every now and then, you can easily substitute the lemon for other citrus fruits such as lime, orange, grapefruit. Or you could even combine them!

Cornstarch (optional)

Lemon curd is thickened by the eggs and it is usually not necessary to add any thickener. But if you need lemon curd that will hold its shape, adding a little bit of cornstarch will help.

When you are planning on using the lemon curd to fill a tart, you need it to be liquid enough to pour into the tart shell but thick enough that you can cut out slices neatly. Adding a little bit of cornstarch helps attain the proper consistency for a tart.

You might find some recipes for lemon tarts that do not contain any thickener (cornstarch or flour). These recipes will usually contain a large amount of butter. When I say large amount, I mean the butter is the dominant ingredient. The butter will thicken the lemon curd once cooled.

If however, the recipe contains a low amount of butter and no thickener, it is more adapted for tartlets or to fill small cups for example. Using this type of lemon curd in a large tart would just leave you with a dripping mess. The curd won’t thicken enough and it will be impossible to cut neat slices of lemon tart.

Butter

Butter will yield a rich and creamy lemon curd that melts in your mouth. Use more or less, depending on your preferences. I have found that the lemon kick is slightly lost when too much butter is added so I prefer recipes with a smaller amount of butter.

Mixing Lemon Curd

I have seen so many different ways of making a lemon curd! Some just mix everything together then heat it. Some will add the butter in the beginning, others at the end. I could go on for a while. But I’ll share with you today my preferred technique, which is very similar to making pastry cream. Except that in this case you are replacing the milk/heavy cream with lemon juice.

Heating Lemon Curd

Here again, there are several options. Some people prefer the slow heat of a double-boiler. They mix everything together in a bowl and place it over a pot of simmering (not boiling) water making sure not to touch the water. I’ve never tried this method because I’m too impatient to take the slower route! And because until I started writing this post I only knew of the direct heat method which works really well for me. If it ain’t broke…!

If you place your pot straight onto the heat, the lemon curd will be ready faster but you should of course pay very close attention to it and keep whisking! I would also recommend heating on medium-low and not higher. Especially if you are making small quantities as the lemon curd can overcook very quickly.

Okay, time to actually make the lemon curd!

Making Lemon Curd

• Heat the lemon juice in a small pot, over medium heat until warm (not boiling). You could add a small portion of the sugar to the juice before heating it. I personally didn’t do this but if you have issues with eggs coagulating too soon, this could be something to consider.
• In the meantime, whisk the eggs with the sugar until slightly lighter in color.

Role of sugar: Sugar will shield the eggs from the acidity of the lemon juice which would otherwise cause the eggs to coagulate early.

• Whisk the cornflour in (sifted if needed) and make sure there are no lumps.
• Add the warm lemon juice slowly to the egg mixture and keep whisking. Careful not to add it too quickly as you don’t want to cook the eggs. By adding it gently you are slowly raising the temperature of the eggs.

• Return to the heat, on medium low and keep whisking until it thickens.

When Is Lemon Curd Done?

• The mixture will initially have a foamy appearance and as you keep mixing the color will intensify and become more uniform.
• If you drag your spatula across the lemon curd, a line should form then quickly close back.
• The curd coats the back of a spatula.
• An instant thermometer should register a temperature of 80-82°C (176-180°F) if not using cornstarch. The temperature will be higher if you added cornstarch. If you want to check the temperature, take the pot off the heat, tilt it slightly and insert your thermometer.

If your lemon curd looks lumpy or you want to get rid of the lemon zest, you can strain it into a bowl at this point through a fine mesh sieve.

Adding the butter

• Once the lemon curd is done, remove it from the heat and add the softened butter cut into pieces. Stir until there are no pieces of butter visible and the cream looks smooth and shiny. It should blend in quite easily but if not, you can use an immersion blender to combine everything together.

Let’s pause for a moment to discuss what you should do if making a recipe with a large amount of butter. Just to clarify, the recipe in this post uses a small amount so the texture and consistency won’t really be compromised, regardless of when you add the butter.

If using a large amount of butter, make sure it has been properly softened to room temperature and do not add it until the lemon curd has cooled to 60°C (140°F).

• Pour the lemon curd into the baked and cooled tart shell. If necessary, smoothen the top with an offset spatula.

Troubleshooting Lemon Curd

Runny lemon curd

• Assuming your recipe proportions are correct and you weighed your ingredients, lemon curd will thicken as it cools down. But if you did cool it down and are unhappy with the consistency, you might have undercooked your lemon curd. Make sure it coats the back of the spoon before removing it from the heat. Solution: Try cooking it again on very low heat or over a pot of simmering water (without touching the water) until it thickens. Although since the recipe contains eggs, you should be mindful of bacterial contamination. If you didn’t cook the curd past 71°C (160°F), I would recommend starting over.

Curdled lemon curd

• The heat might have been too high. Try using a lower heat setting next time or cook the lemon curd over a double-boiler and not direct heat. And don’t forget to keep stirring! Solution: Mix the lemon curd with an immersion blender until smooth, then strain it. If it curdled just a little bit, you can simply strain it.
• Adding lemon juice straight onto the eggs will cause them to curdle. Solution: The sugar protects the eggs from curdling. Add a little bit of sugar to the lemon juice when heating it and mix the remaining sugar with the eggs before adding the lemon juice.

Lemon curd is too thick

You probably cooked it for too long. This might make the lemon curd harder to spread into the tart crust and you won’t have the flat, smooth finish of a lemon tart. Other than the lack of ease spreading it, a thick lemon curd will still taste great and shouldn’t really be an issue. Solution: If you are really unhappy with the consistency you could try thinning out the lemon curd with a bit of liquid such as lemon juice or maybe even some whipped cream. I would suggest trying it out on a small portion before changing completely the consistency and texture of your lemon curd.

Metallic taste or discoloration

If your lemon curd has a strange metallic taste or turned green, you used reactive bakeware (explained at the beginning of the post). I’m sorry to say you should throw out your lemon curd and start over. Solution: Use non-reactive equipment such as stainless steel pots.

And that’s it! So go ahead and grab those lemons. You’ll be enjoying amazing lemon curd before you know it!

This post is part of the tart baking calendar. In case you missed it, head over there to see what tarts we will be making.

Use Lemon Curd With:

• Pâte Sucrée
• Pâte Sablée
• Choux Pastry
• French Meringues