Step by step

1. In the bowl of a Stand Mixer fitted with the Paddle Attachment, combine the granulated sugar and lemon zest. Mix on speed 2 for about 1 minute to infuse the sugar with the lemon flavor.

2. Add the egg yolks to the sugar mixture in the stand mixer bowl. Mix on speed 4 until the eggs are well combined with the sugar and lemon zest. Pour in the freshly squeezed lemon juice and mix until combined.

3. Transfer the mixture to a double boiler and cook over low heat, stirring constantly, until it thickens enough to coat the back of a spoon. This will take about 5-7 minutes. Do not let the mixture boil.

4. Once the mixture has thickened, remove the bowl from the heat and gradually add the cubed butter while stirring until the butter is completely melted and incorporated.

5. Optional: strain the lemon curd through a fine mesh sieve to remove any lumps. Allow the lemon curd to cool to room temperature, then transfer it to a jar or airtight container. Chill in the refrigerator for at least 1-2 hours before using.