In a large pot over medium heat, melt the butter and marshmallows, stirring often, until smooth.

Stir in the Rice Krispies until well coated.

Spread ½ of the Rice Krispie mixture into the bottom of the prepared dish.

Arrange the Oreo Cookies over top of the Rice Krispie layer, then cover with the remaining Rice Krispie mixture.

Melt the white chocolate chips in the microwave in 30-second intervals. Once smooth, spread over the top of the Rice Krispie Treats and sprinkle with your favorite jimmies.