Add the apples to a 3-quart dutch oven and pour the apple cider vinegar, water, and salt over the apples.
Cook over medium heat for about 1 hour. Stir occasionally to keep apples from burning.
When the apples are getting mushy and soft remove the dutch oven from the heat and use an immersion blender to smooth the sauce.
Return to heat and add the brown sugar, cinnamon, and vanilla extract. Stir to mix well and cook on low-medium heat for about 45 minutes or until the apples have reduced to the desired consistency.
Pour apple butter into prepared mason jars. Let cool down, then place lids on the mason jars and refrigerate or freeze.
Notes
Prepare the Jars: Even though this is not a canning recipe, and will just freeze your apple butter, make sure to still sterilize the mason jars in boiling water.Choose the Right Apples: Varieties like Granny Smith, McIntosh, or Braeburn work well. You can also use a mix of tart and sweet apples. The better the apples, the better the apple butter.Add Sweetener Gradually: Start with a small amount of sugar and add more to taste. The sweetness of your apples will greatly affect how much sugar you need.Cook Slowly and Stir Frequently: The key to great apple butter is a long, slow cooking process. This allows the sugars in the apples to caramelize and develop a deep, rich flavor. Prevent sticking and burning and stir frequently.Spice it Up: Add warm spices like cinnamon, nutmeg, and cloves to enhance the flavors. Add them to the end of cooking to keep their flavors vibrant.Blend Until Smooth: Once your apple mixture is thoroughly cooked down, use an immersion blender to mix until smooth. Test for Doneness: Spoon a small amount onto a chilled plate to test if your apple butter is ready. If no liquid separates around the edge, and the apple butter remains mounded, it's ready.BONUS TIP: A slow cooker can make the process easier. You can leave the apples to cook slowly and not worry about them scorching.The recipe can be doubled to make 2 pints (32 ounces)