Gather all your ingredients and equipment before you start; this chaos-free setup makes the process smoother.
Melt the butter in a large saucepan over medium heat until it’s bubbly and fragrant, about 2-3 minutes.
Add the marshmallows to the melted butter and stir constantly with a rubber spatula until they melt completely, creating a smooth, oozy mixture, about 3-4 minutes.
Pour the marshmallow mixture over the Rice Krispies cereal in a large bowl. Quickly and carefully stir to coat all the cereal evenly—this mixture will be sticky and glossy.
Grease your 9x13-inch pan with spray or butter to prevent sticking.
Transfer the mixture into the prepared pan, then press it down evenly with a buttered spatula or a piece of wax paper. Don’t pack it too tight—leave it a little loose for that chewy texture.
Let the treats sit at room temperature for at least 30 minutes to firm up and develop that sticky, chewy consistency.
Once cooled, use a knife or pizza cutter to cut into chunky squares. These treats are best enjoyed slightly warm and gooey.
Serve your monster Rice Krispie treats and enjoy their big, bold, chewy goodness!