Chef John'S Apple Butter - cooking recipe

Ingredients

5 pounds Granny Smith apples, cored and cut into 1-inch pieces
1 1/2 cups white sugar
1/2 cup brown sugar
1 teaspoon salt
2 teaspoons ground cinnamon
1/8 teaspoon freshly grated nutmeg
1/2 teaspoon ground allspice
1/4 cup apple cider vinegar
1 splash water

Preparation

Place apple pieces into a large slow cooker. Add white sugar, brown sugar, salt, cinnamon, nutmeg, allspice, and vinegar. Add a splash of water and mix well.
Cover and cook on High until apples are starting to soften and release liquid, 1 to 2 hours. Reduce heat to Low and cook, uncovered, until all the apple flesh is dissolved, 5 to 6 hours. Stir occasionally.
Puree using an immersion blender until smooth. Continue cooking, stirring occasionally, until darkened and thick, about 4 hours more. Pass apple butter through a strainer if desired. Seal in a glass container and refrigerate until cool.