Peel, core, and slice the apples. Combine with the apple cider in a large heavy-bottomed saucepan, cover, and bring to a simmer. Simmer until the apples are a soft pulp, about 30 minutes.
Pass the apple pulp through a food mill and transfer to a saucepan.
Add the sugar, spices, zest, and salt and simmer, stirring frequently, until very thick, about 2