Lightly grease a 9 x 13-inch pan with nonstick spray.
In a large saucepan over low heat, melt the butter, mini marshmallows, and peanut butter, stirring gently until smooth.
Once melted, remove from the heat and stir in the Rice Krispies until evenly coated.
Press the mixture evenly into the prepared pan.
Melt the chocolate: Place the chocolate chips in a microwave-safe bowl and heat in 20-second intervals, stirring between each, until smooth. Stir in vegetable oil until fully combined.
Pour the melted chocolate over the bars and spread evenly. Let it sit at room temperature until the chocolate is set, about 2 hours.
Cut into squares and enjoy!
Notes
Use your hands to press the mixture firmly into the baking pan. This helps the bars hold together and keeps them compact.
Lightly spray your hands with non-stick cooking spray to prevent the mixture from sticking to your hands while pressing it into the pan.
Store your Peanut butter Rice Krispie treats on the counter at room temperature. Storing them in the refrigerator can make them hard and less chewy.
For easy cutting and cleaner slices, run your knife under hot water before slicing the bars.
Wash your saucepan immediately after cooking for easy clean-up (marshmallows can harden quickly)!
These are best if eaten the day they are made. But you can store them in an airtight container (we try not to eat them all) and store them on the counter for up to three days.They are delicious if they are warmed in the microwave for 10 seconds to freshen them up.