1-First Step: Set up the double boiler Fill the bottom of a double boiler with 1 to 2 inches of water. Bring it to a simmer over high heat, then reduce the heat to low. This gentle heat is important because it helps the Lemon Curd cook slowly without scrambling the eggs. If you do not have a double boiler, place a heatproof bowl over a pot of simmering water, making sure the bowl does not touch the water.

2-Second Step: Whisk the base In the top of the double boiler, combine the 4 large egg yolks, 2/3 cup granulated sugar, 1 Tablespoon lemon zest, 1/3 cup fresh lemon juice, and 1/8 teaspoon salt. Whisk everything together until it looks smooth and combined. A silicone whisk works nicely here because it helps avoid any metallic taste.

3-Third Step: Cook until thickened Whisk constantly until the mixture thickens to a hollandaise sauce-like consistency, about 10 minutes. The curd should start coating the whisk and look glossy. If it is taking longer, keep whisking and give it a little more time. The main thing is gentle heat and steady stirring.

4-Fourth Step: Add the butter Remove the pan from the heat and whisk in the butter pieces one at a time until fully melted. The butter makes the Lemon Curd rich, shiny, and spoonable. Make sure each piece disappears before adding the next one. That helps the final texture stay silky.

5-Fifth Step: Strain if needed The recipe does not require straining, but you can pour the curd through a fine mesh sieve if you want it extra smooth. This is a nice move if a few tiny bits of cooked egg sneak in. It also gives you a polished finish that feels extra special.

6-Final Step: Cool and chill Pour the Lemon Curd into a jar or bowl. Press plastic wrap directly onto the surface so a skin does not form. Refrigerate until cool, which brings the total time to about 1 hour 15 minutes including cooling. Once chilled, it will be ready to spread, dollop, or swirl.