Wash the apples, then peel and core them. Slice into pieces about ½-inch thick so they stay nicely “pie-like” in the jar. If you want to prevent browning while you work, hold the slices in a solution of ascorbic acid and water (or water with a splash of lemon juice), then drain well. This step is optional and only affects appearance.

Bring a separate pot of plain water to a boil and blanch the apple slices for 1 minute, working in batches so the pot stays at a boil. Drain each batch well and transfer the warm apples to a covered bowl or pot to keep them hot while you finish blanching the rest. Keeping the apples warm helps everything stay hot-packed and ready for the jars.

In a large, non-reactive pot, whisk the sugar and cook-type Clear Jel together until evenly combined. Add the cold (or room-temperature) water and apple juice, then whisk thoroughly until the Clear Jel is completely dissolved and the mixture looks perfectly smooth. Don’t shortcut this step. Once Clear Jel starts heating, any dry pockets can turn into little gel lumps that won’t smooth back out.

Set the pot over medium-high heat and cook, stirring constantly, scraping the bottom and corners as you go. As the mixture heats, it will begin to look more translucent and noticeably thicken. Keep stirring until it comes to a full bubble (not just a lazy simmer). When the mixture is bubbling, add the bottled lemon juice, stir well, and continue boiling for 1 minute, still stirring constantly.

Remove the pot from the heat and immediately fold in the drained, warm apple slices. Stir gently but thoroughly so all slices are coated and the filling is evenly distributed. Work promptly from this point forward so the filling stays hot.

Ladle the hot apple pie filling into hot jars, leaving 1 inch of headspace. Use a bubble remover (or a plastic knife/chopstick) to work out trapped air pockets around the fruit, then re-check headspace and adjust if needed. Wipe the jar rims with a clean, damp cloth to remove any syrup or starch residue, then apply two-piece canning lids and screw bands on fingertip-tight.

Load the jars into the preheated canner. The water should be hot/simmering when the jars go in; then bring the canner up to a full rolling boil. Once boiling, start the processing timer and process pints or quarts for 25 minutes, adjusting for altitude as needed.

When the processing time is complete, turn off the heat and remove the canner lid. Let the jars rest in the hot water for about 10 minutes before removing them, which helps reduce siphoning (pie fillings are especially prone to it). After the rest, lift the jars out with a jar lifter and place them upright on a towel, leaving space between jars. Don’t retighten bands and don’t disturb the jars while they cool.

Allow jars to cool undisturbed for 12 to 24 hours. Check seals, then remove bands, label, and store sealed jars in a cool, dark pantry. Refrigerate any unsealed jars and use them first. Refrigerate after opening any jar.