Grate the zest of 1 lemon. Use a small grater and be careful not to include the white part, as it is bitter. Save it for later.

Squeeze the juice from the three lemons into a pot. Add sugar and eggs to the pot.

Whisk the eggs into the lemon juice and sugar.

Cut the butter into cubes and add it to the pot.

Turn on the heat, I set it to 7 out of 14.

Now you must whisk constantly and remember to move along the edges to avoid "scrambled eggs". Use a silicone spatula to get all the way out.

Now the goal is to get the temperature up to between 80-82 degrees Celsius (176-180 degrees Fahrenheit) (not over, otherwise it will separate).

Add the lemon zest and stir well.

A curd should pull together when whisked.

Put it in a sterilized glass jar and place it in the fridge.

Then it sets and is ready for use.