Line a 9 X 13 pan with parchment paper and set aside.
Sort out 1/2 cups of the colorful marshmallows in the cereal. Taste test a few. Set Aside.
Add the butter, vanilla, and the marshmallows to a large pot. Turn the heat to medium and stir constantly until the mixture is completely melted.
Remove the mixture from the heat and quickly toss in the Lucky Charms by gently tossing with a wooden spoon or a rubber spatula until the cereal is completely coated.
Immediately turn the mixture out into the prepared pan and gently press into an even layer using a runner spatula.
Allow the treats to cool for an hour. Cut into squares and serve.