Melt 3 tablespoons of butter over low heat, then add 4 cups of mini marshmallows. Stir constantly until melted, about 3-5 minutes.

Remove from heat and fold in 6 cups of Rice Krispies until fully coated, about 2-3 minutes.

Incorporate 1 cup of drained and chopped maraschino cherries into the mixture and fold until evenly distributed, about 1 minute.

Grease a 9x13-inch baking dish and transfer the mixture, pressing down firmly for an even layer, about 3-4 minutes.

Melt 1.5 cups of chocolate chips in the microwave in short bursts of 30 seconds, stirring until smooth, about 1-2 minutes.

Pour the melted chocolate over the Rice Krispies base and spread evenly, about 1-2 minutes.

Let the treats cool at room temperature until the chocolate hardens completely, about 20-30 minutes.

Once set, cut into squares or rectangles and serve.