Step 1

Fill a medium saucepan 1/3 with water, heat over low/medium heat until simmering.

Step 2

In a medium heat-proof bowl, add the egg yolks, Swerve, lemon zest, lemon juice, vanilla, and salt.

Step 3

Whisk ingredients together and let sit for 2 minutes.

Step 4

Place bowl onto the saucepan and heat, whisking gently for 7-8 minutes or until thickened.

Step 5

Remove from heat and add in cubes of butter then mix until melted and incorporated.

Step 6

Refrigerate until cool.