Add sweetener, lemon juice and zest and stir through until sweetener dissolves.
Whisk in egg yolks and continue to stir over medium heat until the mix thickens and coats the back of a wooden spoon.
Place butter in mixer bowl and melt 3 min/ 90℃/speed 1.
Add sweetener, lemon juice and zest and mix 3 min/speed 3.
Insert whisk attachment. Add egg yolks to mixture and cook 11 min/80℃/speed 3.
Xylitol or Allulose are the only two sweeteners I recommend for this recipe, because other keto compliant sweeteners do recrystallise once refrigerated. If you are making the curd to use on the day, then use any sweetener of choice as long as it is a 1:1 ratio of sweetener to sugar.I have tried a lot of sweeteners in many of my keto curd recipes and unfortunately all of them crystallise to some extent when they are refrigerated. There are a couple of things you can do to reduce the effect on the texture though. If you are making a keto lemon meringue pie, make the curd on the day and only slightly set it in the fridge before topping with meringue, (baking or blow torching) and serving. You can also heat the curd gently, in a saucepan over low heat, to make it smooth and creamy again.You might be tempted to combine all the ingredients together at once, but the trick to smooth and creamy lemon curd is to make sure the sweetener is fully dissolved before whisking the egg yolks in. If you combine the ingredients in just one step, you may find that there is a slightly gritty texture to the curd, which is unpleasant.You can store the lemon curd in the fridge, in an airtight container, for up to 1 week.