Lightly grease a 9x13 inch pan with butter or non-stick cooking spray.

Melt the butter, mini marshmallows, peanut butter, vanilla, and salt together in a large pan over low heat. Gently stir.

Once melted, remove from the heat and add in the Rice Krispies cereal, gently stirring until combined.

Add the mixture into the prepared 9x13 pan, scraping all of it, and then lightly spray your hands with non-stick cooking spray and press the mixture to the bottom of the pan.

Using a medium-sized heatproof bowl, add the chocolate chips and microwave for 45-second intervals on medium power, stirring in between, until almost melted. Make sure and watch this, so it doesn’t over-heat. Next, add in the oil and stir until nice and smooth.

Pour and spread the chocolate mixture over the top of the bars, and allow to harden for about 2 hours at room temperature.

Cut into squares and store in an airtight container at room temperature.