Prepare the Ingredients:

Zest the lemons and then juice them. Ensure you have ½ cup of fresh lemon juice and 1 tablespoon of zest.

Mix the Base:

In a medium saucepan, whisk together the egg yolks, whole eggs, sugar, lemon juice, and lemon zest until smooth.

Cook the Mixture:

Place the saucepan over medium-low heat. Stir continuously with a whisk or silicone spatula, ensuring the mixture doesn't boil, for 8–10 minutes, or until it thickens enough to coat the back of a spoon.

Add Butter:

Remove the saucepan from heat and immediately whisk in the butter cubes, one at a time, until fully incorporated.

Strain the Curd:

Pour the lemon curd through a fine-mesh strainer into a heatproof bowl to remove any cooked egg bits and ensure a silky texture.

Cool and Store:

Allow the lemon curd to cool to room temperature, then transfer it to a jar or airtight container. Refrigerate for at least 2 hours to fully set.