Step 1

Place eggs, sugar, salt, juice, and zest in a medium saucepan. Do not put it over the heat yet. Whisk the ingredients together until smooth.

Step 2

Place over low heat. Stir constantly with a wooden spoon until the mixture thickens, about 4-5 minutes. Turn all the way to low and add the butter. Stir until smooth.

Step 3

Remove from heat and pour into jar(s). Makes just shy of 2 cups.