Add the apples (seeds and all), cranberry juice, ginger and cinnamon stick to a large pot. Bring to a boil, then reduce the heat and steep on medium until the apples are mushy, about 25 minutes. Strain the contents of the pot using a fine-mesh sieve and a moist paper towel or cheesecloth. Do not press anything through the sieve. Allow to drip to about 2 cups of liquid. Discard the solids.
Wipe the pot clean or rinse with water. Pour all but 1/4 cup of the liquid back into the pot and add the sugar. Cook on medium high until the sugar dissolves.
Add the gelatin to the reserved 1/4 cup liquid and stir. Stir this into the pot and remove from the heat. Let cool until just warm.
Coat the inside of four 8-ounce ridged party cups (or several shot glass-size party cups) with cooking spray (you may want to double the cups so you don't warp them). Once the liquid has cooled a bit, divide among the cups. Place on a tray and refrigerate until firm, about 3 hours.
To unmold, dunk the sides of the cups in warm water and wiggle out the jelly.