Blanch apple slices by dipping them in a large pot of boiling water for 1 minute. Drain set aside.
Combine sugar, clear jel, cinnamon, and nutmeg (if using) in a large pot. Whisk in the cold water and apple juice. Set over medium high heat and cook, stirring almost constantly, until mixture thickens and begins to boil.
Add the bottled lemon juice and cook for 1 minute. Remove from heat. Mixture will be very thick.
Add the blanched apples to the mixture and immediately ladle into hot sterilized jars, leaving 1 inch headspace at the tops of the jars. Remove air bubbles with a long knife or thin spatula. Wipe rims and cover with lids and ring bands.
Process in a large pot of boiling water for 25 minutes (see notes for high altitude processing time). Make sure jars are completely covered by the water and water is at a rolling boil for the entire processing time.
Let jars cool and ensure lids have sealed (lids should not bounce back when pressed). Store any unsealed jars in the fridge and use within a few weeks.
To bake a pie, simply pour it into a prepared pie shell. Bake at 400°F until filling is bubbling and crust is golden brown.
Store sliced apples in a solution of water and lemon juice (2 tablespoons lemon juice per large bowl of water) to prevent browning until ready to proceed with recipe.
Increase processing time for high altitude as needed: 1,001-3,000 ft 30 minutes, 3,001-6,000 ft 35 minutes, 6,001+ ft 40 minutes.