Prepare jars by washing them in hot soapy water and keeping them warm.
Peel, core, and slice apples. Place slices in water with a little lemon juice to prevent browning.
In a large stockpot, combine sugar, cornstarch, cinnamon, nutmeg, salt, and water.
Cook over medium heat, stirring constantly, until the mixture thickens and begins to bubble.
Stir in bottled lemon juice and boil for 1 minute.
Add drained apple slices to the hot syrup and simmer for 5–8 minutes until slightly tender. Do not overcook.
Using a ladle and funnel, pack hot apple filling into warm jars, leaving 1 inch headspace.
Remove air bubbles and wipe jar rims clean.
Apply lids and bands until fingertip tight.
Process jars in a boiling water bath canner for 25 minutes (adjust for altitude if needed).
Remove jars and let cool undisturbed for 12–24 hours.
Check seals before storing in a cool, dark place for up to 1 year.
