Measure the erythritol and arrowroot powder and put them in a medium pot. Stir together.
Roll the lemons on the counter to get them juicy, then zest the lemons adding the zest to the erythritol.
Separate 4 eggs and add the yolks to the erythritol in the pot. Add the 4 whole eggs to the pot and whisk the eggs and erythritol together.
Juice the lemons and measure 3/4 cup. Strain the lemon juice and stir it into the eggs.
Turn the heat to medium and continuously whisk the mixture until it begins to thicken - it only takes a few minutes. Turn the heat down to medium-low and continue whisking. The lemon curd will thicken - all at once
Remove the pot from the heat and continue to stir with the whisk for one minute more. Pour into a clean container and add the stevia glycerite and salted butter incorporating completely.
To cool, place a piece of plastic wrap right on top of the low carb lemon curd and refrigerate. I like to make a water and ice bath in a larger bowl, set the bowl with the lemon curd inside of the bigger bowl and stir the lemon curd until it is cool.
Store in an airtight container and refrigerate up to 2 weeks.
Makes about 2 cups. Serving size is about 3 tablespoons with 2.5 net carbs per serving.