Prepare a 9x13 pan with non-stick spray. Melt the butter in a large pot over medium heat. Add the marshmallows and stir until fully melted in the butter. Stir in the green food coloring. Remove the pot from the heat and stir in the rice cereal. Add to the prepared dish and press into the pan as much as you can. Place the pan in the fridge for 10 minutes to cool.
Turn the pan upside down on top of a cutting board or counter. Use the cookie cutter to cut out as many shamrocks as you can.
Use gel frosting and sprinkles to decorate the shamrocks with fun faces. Enjoy!
Notes
You can use regular marshmallows instead of lime and lemon-flavored marshmallows. Below is a photo of the marshmallows I used. You will need two bags and you do have to separate the flavors, but my son and I had fun doing it!😁
These treats can be stored in an air-tight container for 3-4 days.
Nutrition estimates are for Rice Krispie Treats ONLY.