In a large saucepan, melt the butter over low heat.

Add the mini marshmallows to the melted butter, stirring constantly until completely melted and smooth.

Remove the saucepan from heat and add a few drops of green food coloring to the mixture. Stir until evenly colored.

Gradually mix in the Rice Krispies cereal until fully coated with the marshmallow mixture.

Transfer the mixture to a greased 9x13 inch baking dish. Press down firmly to create an even layer.

Allow the mixture to cool for about 10-15 minutes.

Once cooled, cut into squares or use cookie cutters for spooky shapes.

Decorate with black food coloring, chocolate chips, or candy eyes for a truly creepy effect!