Grease a 9×13 inch pan with butter or pan release spray. Set aside.
Add the marshmallows, granulated butter flavoring, water, vanilla, and salt to a medium sized saucepan, and mix on medium heat until fully melted.
Remove the mixture from the stove, and add in your Rice Krispies cereal and stir until evenly mixed in.
Stir in the Lucky Charms marshmallows (optional). *TIP: We set a few of the Lucky Charms marshmallows aside to top the Rice Krispies treats once placed in the pan.
Pour your mixture into your greased 9×13 inch pan. With a greased spatula, press the rice krispies down until flat. Top with remaining Lucky Charms marshmallows. Let cool completely.
Cut Rice Krispies treats into squares, and serve!
