Grease a 12-cup muffin pan.
In large pot, melt butter over medium heat.
Add mini marshmallows, stirring until completely melted into the butter over medium-low heat. Make sure not to burn.
Add a few drops of red and yellow food coloring until you have your preferred shade of Halloween orange.
Add Rice Krispie Cereal to the pot, and stir with a greased rubber spatula until fully combined.
Using the greased rubber spatula, fill each muffin cup to the top, pressing down firmly to compress the Rice Krispies.
Place muffin pan in refrigerator for 30 minutes, or until set.
Cut the Kit-Kat bars into three equal pieces.
Take each Rice Krispie treat out, and use your hands to gently round out the edges and form a “pumpkin” shape.
Take a butter knife and carve out a small hole in the top of each pumpkin, and insert a Kit-Kat piece into the hole.
Draw a face on each pumpkin with the writing gel. (Wait until just before serving before doing this step so the faces don't smear.)