Melt the butter in a large saucepan over low heat.
Add the mini marshmallows and stir continuously until completely melted.
Place a few drops of food coloring in the melted marshmallows and stir, adding more food coloring until you reach your desired shade.
Add the Rice Krispies cereal, making sure to evenly coat all of the cereal with the melted marshmallow mix.
Allow the Rice Krispies to cool for about 15 minutes (I usually transfer them to a 9x13 baking pan, it takes longer for them to cool if they remain in the warm saucepan).
Carefully shape sections of the Rice Krispies treats into carrot shapes. I usually use about a cup of the treat mix per carrot.
Roll and twist pieces of the fruit leather to create the green stalk of the carrot. Carefully place on top of the Rice Krispies carrot (sometimes I find it easier to sort of smush the Rice Krispies up around the fruit leather to hold it in place).
Place the finished Rice Krispies treats on a baking sheet lined with parchment or wax paper and cover with plastic wrap until ready to serve.