Put a hot water bath canner on the burner and fill with enough water to cover jelly jars, with an extra inch of water over the top of jars. Turn the burner on high and cover with the lid.
Wash jelly jars and screw bands. Place jelly jars in the canner to sterilize.
While you wait for the water bath to come to a boil, prepare your fruit. Peel, core, and dice the apples. Wash the cranberries and chop them coarsely.
When the water in the canner comes to a full rolling boil, boil jelly jars for 20 minutes to sterilize them.
Measure the pectin into a small bowl and add 1/4 cup of the sugar. Combine and set aside.
Measure the rest of the sugar into a medium bowl and set aside.
Prepare canning jar lids according to the manufacturer's directions. (Most jar lids are no longer designed to be boiled, be sure to check.)
Once the water bath with jelly jars comes to a full rolling boil, set a timer for 20 minutes.
Place prepared fruit and water in a large saucepan turn burner to medium-high.
Cook until fruit is tender and comes to a rolling boil.
Add pectin mixture and stir in. Continue stirring to prevent burning.
Bring to a rolling boil and add the remainder of sugar all at once. Stir in and continue stirring.
Return to a rolling boil and boil for 1 minute.
Use a jar lifter to remove sterile jelly jars from canner and place them on a heavy towel on your countertop.
Place a canning funnel in a jelly jar and use a ladle to fill with apple jam. Work quickly but carefully to prevent the jam from cooling.
Wipe rim of jar clean, place canning lid on the jar, then screw canning band in place until finger tight.
Use the jar lifter to place the filled jar into the boiling water bath.
Repeat until all of the jam has been placed in the canner. Place lid on the canner and return to a full rolling boil.
Process jam for 10 minutes once the water returns to a full rolling boil.
Remove jars from canner with the jar lifter and place them on a heavy towel to protect your countertop. Allow the jam to cool without disturbing the jars or screw bands until jam reaches room temperature.
When the jam has cooled completely, remove screw bands and wash the jars to remove any jam that may have leaked during processing. Check each jar to be sure it has sealed properly. A properly sealed lid will not spring up and down when pressed with your fingers.
If any of the jars did not seal properly, refrigerate them and use the jam within 3 weeks.