Put a couple inches of water in a pot and bring the water to a boil, then reduce the heat to a simmer.

Place a heatproof glass bowl over the pot, making a double boiler.

In the same glass bowl, whisk together the lemon juice, sugar, salt, lemon zest, egg yolks, and whole egg.

Cook the curd mixture for 10-15 minutes, stirring constantly, until it coats the back of a spoon.

Remove from the heat and whisk in the butter for about a minute, or until it's fully emulsified. (If it's not fully emulsified, it may cause the curd to be grainy.)

If the eggs have curdled at all, you can pour the curd through a fine mesh strainer to get it smooth, but this may remove the lemon zest as well.

Place the finished curd in a jar or container and cover with a lid. Chill in the fridge until it’s cold and set. This recipe makes between 1 and 1 1/2 cups of curd.

Enjoy with yogurt, toast, or even as a topping for vanilla ice cream.