Core and Dice the Apples - Core 2.2 pounds of apples and dice them into small, even pieces. Leave the skins on and place the apples in a large saucepan. Even pieces help them cook evenly.
Add the Water, Sugar, and Lemon Juice - Add ½ cup water, ¼ cup granulated sugar, and 2 tablespoons lemon juice to the apples. Set the pan over medium-high heat and bring to a boil, stirring as needed.
Cook the Apples Until Soft - Reduce the heat to medium-low, cover, and cook for about 45 minutes. Stir occasionally until the apples are very soft and mushy. The liquid should also reduce during cooking.
Cool the Apples Before Blending - Remove the pan from the heat and let the apples cool for 5 minutes. Transfer them to a blender once they have cooled slightly.
Blend Until Very Smooth - Blend the cooked apples until smooth and creamy. Return the puree to the saucepan.
Add the Cinnamon, Brown Sugar, and Salt - Stir in 1 teaspoon cinnamon, 2 tablespoons brown sugar, and ¼ teaspoon sea salt. Mix well until everything is evenly combined.
Cook Until Thick and Deeply Colored - Cook the apple puree over low heat for about 30 minutes, stirring often. It should become thick, spreadable, and deep caramel in color.
Store Before Serving - Remove the apple butter from the heat and let it cool. Transfer it to a jar or airtight container. Once cooled, cover and refrigerate.