01 - In a large, heavy-bottomed pot, combine chopped apples, lemon juice, apple cider, and water. Bring mixture to a simmer over medium heat and cook for 10 minutes, stirring occasionally, until apples are tender.
02 - Using a potato masher or immersion blender, gently mash the apples to create a slightly chunky texture.
03 - Add granulated sugar, brown sugar, ground cinnamon, nutmeg, allspice, and salt. Stir thoroughly until sugars dissolve completely.
04 - Add unsalted butter. Continue cooking on medium heat, stirring frequently, until mixture thickens and turns a golden caramel hue, about 20 to 25 minutes. Stir gently and scrape the bottom to prevent scorching.
05 - Bring mixture to a full boil. Stir in the liquid pectin, then boil rapidly for 1 to 2 minutes. Remove the pot from heat.
06 - If needed, skim off foam from the surface. Ladle hot jam into sterilized jars, leaving 1/4 inch headspace. Wipe rims, apply lids, and process jars in a boiling water bath for 10 minutes, adjusting time for altitude if necessary.
07 - Let jars cool completely. Store in a cool, dark location. Refrigerate after opening.