In a large bowl, mix together the pumpkin, cream cheese, pumpkin pie spice and brown sugar with an electric mixer until thoroughly combined, about 2 minutes.
In a separate bowl, or in the bowl of a stand mixer, beat the heavy cream and powdered sugar until light and fluffy, about 5 minutes.
Layer the parfait ingredients into mason jars in this order: graham crackers, pumpkin cream cheese mixture, whipped cream. Continue to layer to fill the jar, at least 2 layers of each ingredient.