1. Spray the bottom of an 8×8 pan with cooking spray and line with parchment paper or wax paper. 
2. In a saucepan over low-medium heat, melt 2 tablespoons unsalted butter. 
3. Stir in 3 cups mini marshmallows, reserving the remaining ½ cup, and stir continuously until melted. 
4. To a large mixing bowl, add 3 cups of Lucky Charms cereal. 
5. Once your marshmallow mixture is melted and smooth, remove from the heat and pour into your mixing bowl with the cereal.
6. Add in the additional ½ cup reserved (unmelted) marshmallows.
7. Stir, mixing until the cereal is coated. 
8. Once combined, quickly transfer the cereal mixture to your lined and greased pan and push it down to evenly spread it. The marshmallows will set fast. Use a greased spatula or grease your hand to help even out the mixture and avoid sticky hands. 
9. Let cool for at least 30 minutes. 
10. Cut into 6 large bars or 12 smaller bars. 

Optional Chocolate Coating:

1. Melt your white melting chocolate/wafers according to instructions. If using chocolate chips, add in a dash of heavy cream and heat it in the microwave in 15-30 second intervals stirring after each interval to avoid burning or seizing. 
2. If using sticks, dip the tip of your cake pop stick or popsicle stick into the melted chocolate and insert it halfway into the bar. 
3. Let dry for 2-3 minutes before fully dipping the bar or drizzle the chocolate on top.