For the pupil and iris: Spray a 3-quart mixing bowl with nonstick cooking spray. Combine the blue gelatin with the boiling water in a small bowl and mix until the gelatin is completely dissolved. Pour 1/4 cup of the gelatin into a second bowl and mix in the black food coloring. Set the remaining blue gelatin aside. Pour the black gelatin into the prepared bowl.
Place in the refrigerator to set, about 30 minutes. Use a 2 1/4-inch round cutter to cut the gelatin into a circle and carefully remove the excess gelatin from around the outside of the cutter to leave a "pupil" in the bottom of the bowl. Discard the excess gelatin.
Pour 1/4 cup blue gelatin into the bowl over the black pupil (if the blue gelatin has set before pouring, pop it in the microwave for 10 to 15 seconds to loosen it). You will have some excess blue gelatin. Place the bowl back in the refrigerator to set another 30 minutes.
For the eyeball and crust: Combine the cheesecake mixes and milk in a large bowl. Blend with an electric mixer until thick but still pourable, about 2 minutes. Pour the batter into the bowl over the pupil and iris. Gently drop the bowl on your counter a few times to release any air bubbles. Place in the refrigerator and let set for 1 hour.
Meanwhile, mix together the melted butter and red gel food coloring and whisk to ensure that the food coloring is completely blended into the butter. Combine the sugar, red melted butter and 2 bags of the crushed graham crackers that came with the no-bake cheesecake mix in a bowl and mix with an electric mixer on medium-low speed until the graham cracker crumbs are colored red, about 2 minutes.
Remove the eyeball from the refrigerator and press the crust on top. Place the entire eyeball cake back in the refrigerator to let the crust harden, about 1 hour.
To plate and garnish: Place a large round plate or platter over the bowl with the eyeball cake. Flip the bowl over so the bowl is on top of the plate. Gently tap the bowl and plate on the counter to help release the eyeball. Gently remove the bowl to reveal the eyeball cake (if the cake does not release from the bowl, dip the bowl in warm water to help it loosen).
Use the red writing gel to make branching lines around the eye to resemble the veins of a bloodshot eye. Spoon the cherry pie filling around the entire base of the eyeball (you may not use the whole can).