In a large stockpot, melt the butter over medium heat. Once fully melted, add the marshmallows, stirring continuously until they are melted, and the mixture is smooth and creamy.

Remove from heat. Add 8 drops of yellow food coloring, and stir well. Pour the Rice Krispie cereal into the pot, and mix well.

Line a 9x13 baking dish with parchment paper. Pour the rice crispy mixture into the baking dish. Using a rubber spatula, press down the mixture as much as possible.

A really helpful trick is to wrap a piece of aluminum foil around your hand. Lightly spray the foil with cooking oil, and then press the rice crispy mixture into all corners of the dish, and flatten well. Set aside to allow the rice crispy mixture to slightly harden.

In a small glass bowl, add the semi-sweet chocolate chips. Heat in the microwave for 30 seconds at 50% power. Stir well, and if needed, microwave an additional 10 seconds at 50% power. Let cool slightly.

Holding a ziploc bag open in the palm of your hand, add the melted chocolate into the bag. Close the bag, leaving one corner open so that air can escape. Using kitchen shears, make a very small diagonal cut to the corner where the chocolate is in the bag to create a piping bag.

Lift the parchment paper with the rice crispy treats out of the baking dish, and onto a cutting board. Using a large knife, cut the treats into 12 squares. On each square pipe two chocolate circles touching each other for the eyes.

Make three eyelashes on each eye, and then make a half circle for the nose. Draw the mouth and the outline of two teeth, and then set the chocolate bag aside.