Melt 4 tablespoons of butter in a large saucepan over low heat until fully melted and bubbly.

Add 10 ounces of mini marshmallows to the melted butter, mixing continuously until melted, about 3-5 minutes.

Stir in 6 cups of Rice Krispies cereal until well-coated with the marshmallow mixture.

Fold in 2 cups of Lucky Charms cereal gently to avoid crushing the marshmallows.

Transfer the mixture into a greased 9x13 inch baking dish and press down evenly.

Cool for about 30 minutes at room temperature until set.

Optional: Drizzle with melted chocolate before serving.