Warm the butter gently in a pan just until it melts. Do not let it get hot.
Add the eggs, lemon juice, sweetener, lemon zest and Keto Chow to a blender and blend.
Scrape down the blender as needed and continue to blend until thoroughly mixed.
Turn the blender to low, and pour the melted butter through the hole in the lid until mixed in.
Pour the lemon mixture back into the pan that you melted the butter in and cook the curd, stirring constantly, over a low heat until it becomes very thick and coats the back of a spoon—about 10 minutes.
Place a sieve over a large bowl and pour the lemon curd through the sieve to remove any lumps.
Transfer the curd to a container to store it in.
Leave the curd at room temperature until completely cold. Either cover the curd with parchment or stir every 10 minutes to prevent a skin from forming.
Once cold, cover and keep in the fridge.**