Start by greasing a 9x13-inch baking dish with butter or cooking spray to prevent sticking.

In a large saucepan, melt 4 tablespoons of butter over low heat. Add 10 ounces of mini marshmallows, stirring continuously for about 5 minutes until smooth.

Remove the saucepan from the heat and stir in a few drops of green food coloring until you reach the desired hue.

Carefully fold in 6 cups of Rice Krispies into the melted marshmallow mixture, mixing for about 2-3 minutes until well coated.

Transfer the mixture into the prepared baking dish, using a spatula to press the mixture evenly into the dish.

Melt 8 ounces of white chocolate in a microwave-safe bowl, stirring in intervals until smooth, then pour over the Rice Krispie mixture.

While the chocolate is warm, sprinkle rainbow sprinkles over the top to create a festive appearance.

Let the treats cool at room temperature for about 30 minutes, then cut into squares or rectangles.