Drain 15 cups frozen red tart cherries, thawed in a colander and placed over a large bowl to drain. Set 4 cups of the liquid and the cherries aside (discard remaining cherry juice or save for another use).
To prepare jars: place jars (without lids or rims) in an upright position in a water canner or large stockpot with a rack and fill with hot water. Cover the jars with water by about 1 inch. Cover with a lid and bring to a simmer; keep jars in a low simmer until ready to fill. Place lids in a separate saucepan and keep on low heat to keep warm for sealing. Leave clean bands nearby.
Whisk together the 4 cups of cherry liquid, 3 ½ cups granulated sugar, 1 cup ClearJel cook type* and 1/2 tsp ground cinnamon in a large saucepan. Bring to a boil over medium-high heat, stirring constantly. Boil until thickened and mixture begins to bubble. Add 1/4 cup lemon juice
Return to a boil and boil for 1 minute, stirring constantly. Add reserved cherries and 1 tsp amaretto liqueur, or flavoring. Return to a boil, stirring constantly but gently. Remove from heat.
Using a ladle and funnel, carefully spoon hot pie filling into jars and leave 1” headspace at the top. Use a knife or skewer to remove any large air pockets. Wipe each rim of jar with a clean kitchen towel or paper towel. Then place a warm lid on top and then a band and screw on tight. *Any pie filling that does not fill an entire jar will need to be refrigerated for immediate use.
Place filled jars back into water canner or large stockpot using tongs or jar lifter. Ensure jars are still covered by at least 1" of water.
Place lid on water canner or stockpot and bring to a full boil. When the water is boiling, set timer and allow jars to process for 35 minutes for an altitude or 1000-3000 ft of elevation *see notes below to adjust processing time according to your current altitude
Remove from heat, take lid off water canner or stockpot and allow jars to sit in water 5 minutes. Then, carefully lift jars out using jar lifter or tongs and place on a kitchen towel and dry them off.
Check to see if the jars are sealed by pressing down on the top of each lid. It is firm and does not move, it is sealed. Jars can still "pop" (seal) for several hours after removing from water bath after processing. If the lid still bounces after several hours, it is unsealed and will need to be refrigerated for immediate use.