In a blender pulse the butter, sugar and zest until combined.

Add the eggs, one at a time then the lemon juice and blend until smooth.

Pour into a saucepan and cook over low heat, stirring constantly.

Use a thermometer to see when the curd hits 170 degrees, about 10-15 minutes.

The mixture should just be beginning to thicken. If you're using it for a tart you may cook a little longer for a thicker curd as shown in the photo.

Remove from the heat and allow to cool then place in a jar, seal and store in the refrigerator to use for the next few weeks.