Bring a medium pot of water to a boil over high heat. Add the chicken breasts and reduce the heat to medium-high to maintain a low boil.
Cook the chicken breasts for 20 to 25 minutes, until cooked through. Transfer the chicken breasts to a cutting board and let sit until cool enough to handle.
Roughly chop the chicken breasts into chunks. Add to a blender, along with 1 cup water.
Puree the chicken, adding an extra 1 to 2 tablespoons water as needed until the consistency is smooth.
Transfer to a small bowl, let cool, and then serve or store until ready to use. Store in an airtight container in the refrigerator for 3 to 5 days or in the freezer for 4 to 6 months.