In a large mixing bowl, combine melted butter and mini marshmallows. Microwave in 30-second intervals until melted and smooth.

Stir in the rice cereal until fully coated. Allow to cool slightly.

Lay a sheet of parchment paper on a rolling mat. Spread the rice cereal mixture evenly over the parchment, pressing down to form a rectangle.

In a separate bowl, mix crushed Oreos with softened cream cheese. Spread this mixture over the rice cereal layer.

Using the rolling mat, carefully roll the mixture tightly into a log shape.

Slice the rolled treat into sushi-sized pieces. Dip each piece in melted chocolate and sprinkle with additional sprinkles if desired.

Serve immediately or refrigerate until ready to serve.