Step 1

Grease a 9 inch by 13-inch pan with butter or spray with baking spray.

Step 2

Combine the butter and marshmallows in a large microwave-safe mixing bowl.

Step 3

Heat in the microwave for 1 minute then remove and stir vigorously until melted.

Step 4

If needed, heat for additional 15-second increments stirring after each until melted.

Step 5

Stir in the Rice Krispie Cereal and press gently into an even layer in the buttered pan.

Step 6

Grease a large mixing bowl with butter or baking spray and pour in the cereal.

Step 7

Begin melting the butter in a medium-large saucepan set over low heat then stir in the marshmallows.

Step 8

Continue to melt over low heat, stirring often, until about 75% of the marshmallows have melted.

Step 9

Remove the pan from the heat and stir vigorously until all of the marshmallows have melted.

Step 10

Pour the melted marshmallows over the Rice Krispies Cereal and toss to evenly coat.

Step 11

Spread the mixture into the buttered pan and gently press into an even layer.

Step 12

Let the cereal treats cool for at least 30 minutes before cutting into 18 rectangles.