In a large saucepan, melt the unsalted butter over low heat.
Add the mini marshmallows to the melted butter, stirring continuously until the marshmallows are completely melted and the mixture is smooth.
Stir in the chocolate chips until they are fully melted and incorporated into the marshmallow mixture.
Remove the saucepan from heat and stir in the vanilla extract and a pinch of salt if desired.
In a large mixing bowl, combine the crispy rice cereal with the chocolate-marshmallow mixture, ensuring the cereal is evenly coated.
Press the Chocolate Rice Krispies mixture into a greased 9x13-inch baking dish, creating an even layer.
Allow the Chocolate Rice Krispies to cool and set for at least 30 minutes.
Once completely cooled and set, cut the Chocolate Rice Krispies into squares or desired shapes.
Serve and enjoy these delectable Chocolate Rice Krispies, relishing the perfect blend of crispy rice and rich chocolate flavor in this delightful treat!