To make a lemon layer cake special, lemon curd spread in between the layers as a filling or mixed into the frosting will do wonders. It is a lemon, butter, sugar, and egg combination that is cooked until thickened, just like a custard.
Lemon curd comes to us from British cuisine, dating back to somewhere around the 19th century. You can eat it like jam by spreading it over bread, especially toast. While that is a tasty way of using it, my concentration has been on folding it into cake frosting and using it as a filling for cakes and tarts. There are many recipes out there for lemon curd, but an easy recipe I’ve stuck with over the years has been one that uses whole eggs. It has a light and creamy consistency that is great for folding into whipped cream, which makes for a tangy cake filling. For thicker curd, egg yolks should be used without the whites, or a combination of whole eggs and egg yolks. I can see that kind of curd to be useful as a filling for macarons. Sounds like something I need to put on my to-do list!
Following is the recipe and afterwards are step-by-step instructions with photos.
For this curd, use 2 large lemons. Zest the lemons first and set aside the zest to add to the curd after cooking. Cut the lemons in half and squeeze out the lemon juice into a small bowl. Strain the lemon juice through a finely meshed sieve (to catch any seeds and pieces of pulp) into a small pot. Add 6 tablespoons softened butter, 1 1/4 cups sugar, and 3 whole eggs to the pot. Set the pot on the stove over medium-low heat. Begin whisking.
You should whisk constantly while the pot is over the heat. In the beginning as you whisk, you will see the butter break up into small pieces as the butter melts. After the butter melts completely, you should have a smooth mixture that should not curdle or turn to lemony scrambled eggs–but keep whisking.
Whisk until the mixture thickens and coats the back of a spoon (or silicone spatula!), about 15 to 20 minutes.
Remove from the heat. Mix in the reserved lemon zest either in the pot or after transferring into a small bowl.
Cover the bowl with plastic wrap, lightly pressing the plastic wrap onto the curd. Refrigerate for at least 2 hours before using. Makes 1 3/4 cups lemon curd.
If not using immediately, transfer the curd to a jam jar and store in the refrigerator for up to 1 to 2 weeks. Lip-smacking good!