Chocolate Peanut Butter Rice Crispy Treats

0 Lightly grease a 9 x 13-inch pan with nonstick spray. 
1 In a large saucepan over low heat, melt the butter, mini marshmallows, and peanut butter, stirring gently until smooth. 
2 Once melted, remove from the heat and stir in the Rice Krispies until evenly coated.
3 Press the mixture evenly into the prepared pan.
4 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. 
5 Pour the melted chocolate over the bars and spread evenly.  Let it sit at room temperature until the chocolate is set, about 2 hours. 
6 Cut into squares and enjoy!