Preheat oven to 350°F and place liners in 24 cupcake tins.

Combine cake mix, water, oil, and eggs in a medium mixing bowl and stir until well blended.

Bake according to cake mix directions. Allow cupcakes to cool completely, then remove the liners.

Gently push a cupcake into each cauldron, pushing down enough so that there is room for the pudding on top of the cupcake.

Whisk the pudding mix and milk together in a medium bowl until fully incorporated, then add a few drops of neon green food coloring, adding a drop or two at a time to achieve desired color, and whisk until color is uniform throughout pudding.

Add the green pudding on top of the cupcake in each cauldron; do not overfill.

Chill in the refrigerator for at least 2 hours.

Melt the butter in a large pot over medium heat, then add marshmallows and stir continuously until marshmallows are completely melted.

Stir a few drops of green food coloring into the melted marshmallows and mix well. The color will get a little lighter when the Rice Krispies are added, so make sure the green is fairly dark.

Add the Rice Krispies to the marshmallows and stir until all the cereal is evenly coated.

Immediately put a spoonful of Rice Krispy mixture on top of the pudding in each cauldron. Do this before the marshmallows start to cool or it will be difficult to place them on the pudding.

While Rice Krispies are still warm, top with Halloween sprinkles.