Prepare a baking pan by greasing it lightly.
Melt the butter in a large pot over low heat.
Add the mini marshmallows to the melted butter and stir until fully melted.
Remove the pot from heat and stir in the vanilla extract and salt.
Fold in the Rice Krispies and Lucky Charms until well coated.
Transfer the mixture to the prepared baking pan, pressing down firmly but gently.
Allow the treats to cool completely before cutting into squares.
Enjoy your Lucky Charms Rice Krispie Treats as a fun and delicious snack!