Add brown sugar, butter, pumpkin pie spice and marshmallows to a microwave safe bowl and heat for 1 minute or until marshmallows are melted and softened.

Stir mixture together then add rice crispies to the bowl.

stir together well then press into a 9 x 13 pan.

If adding pecans, sprinkle the tops with pecans and gently press into the tops as you press down and smooth the treats into the pan.

Sprinkle tops with a little cinnamon, allow to cool then slice and enjoy!