In a medium bowl, whisk together the pineapple juice, sugar, and eggs until well combined.
Transfer this mixture to your slow cooker.
Add the cubed butter to the slow cooker.
In a small bowl, mix the cornstarch and water until smooth, then add it to the slow cooker.
Pour in the lemon juice and mix everything together gently.
Cover and cook on the LOW setting for 2-3 hours, stirring every 30 minutes to prevent any curdling and to ensure even cooking.
After 2-3 hours, the mixture should be thickened and coat the back of a spoon. If it’s not quite thick enough, continue to cook in 30-minute increments, stirring occasionally.
Once thickened to your liking, transfer the curd to a blender and blend until silky smooth (be cautious with the hot mixture).
Pour the curd through a fine-mesh sieve to remove any remaining bits of egg or cornstarch lumps.
Transfer the strained curd to sterilized jars and allow it to cool completely. Store in the refrigerator for up to two weeks.
