Pumpkin Pie Rice Krispies Treats

Coat an 8-inch round cake pan with cooking spray. Set it aside. Add the butter to a medium saucepan set over medium-low heat. Once the butter has melted, add the marshmallows and cook, stirring constantly, until the marshmallows are melted. Stir in the vanilla extract and then the Rice Krispies cereal until the cereal is well coated. Transfer the mixture into the prepared cake pan an press it firmly against the inside edge of the pan to form about a 1-inch crust. Let it cool while you prepare the filling.