Spray two 12-cup regular muffin tins with non-stick spray. Set aside.
In a large saucepan, over medium heat, melt a half stick (1/4 cup) of butter. When butter is almost completely melted, add in 8 ounces (half bag) of the mini marshmallows. Stir constantly until marshmallows start to melt.
Squeeze in 3 to 4 drops of yellow food dye (more or less, depending on how dark a yellow color you want). Stir well to combine the color into the melted marshmallows. Remove from heat.
Pour 3 cups of the crispy rice cereal into the yellow marshmallow mixture, quickly but gently stir to combine. (The next part is sticky! So be patient, and use non-stick spray on your spoon to help distribute the mixture into the tins.) Add 2 to 3 Tablespoons of yellow Rice Krispies mixture into the bottom of each of the muffin cups.
Using the back of a greased spoon, press the mixture into the bottom of the cups. Repeat with all 24 muffin cups. Set aside.
In a separate large saucepan, over medium heat, melt the remaining butter (1/2 cup). Once butter is almost melted, pour in 1 (16-ounce) bag of marshmallows into the melted butter. Stir constantly until marshmallows are just about melted, and then squeeze in 3 to 4 drops of orange food dye. Stir well to combine the color into the melted marshmallows. Remove from heat.
Pour in 6 cups of the crispy rice cereal into the orange marshmallow mixture, and quickly but gently stir to combine. Take 1/3 cup of the orange Rice Krispies mixture and place it into each muffin cup, on top of the yellow mixture. Repeat with all 24 muffin cups. Then, with the back of a greased spoon, press the orange mixture into the cups. Let them stand for at least an hour or two to let the rice krispie cupcakes set. (Or you can loosely cover them with Saran Wrap, and place them in the fridge for 30 minutes.)
Meanwhile, pour the container of vanilla frosting into a medium bowl. Add in the cup of powdered sugar, and using a whisk, whisk together until all is combined. Scoop frosting mixture into a decorating bag fitted with a tip of your choice (or you can use a sandwich baggie and cut off one side).
Gently remove each Rice Krispies cupcake from the pans. (They should come out very easily.) Pipe frosting onto each cupcake and decorate each with a candy corn, if desired. Serve and enjoy!