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.
Serve chilled.
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Notes
Crush it: Crush the grahams right in their package! If you are worried it will split open or the kids will be a bit too enthusiastic, you can also use a plastic zippered baggie.
Keep it cold: Make sure your cream is very cold so that it whips up easily.
Mix well: Let the cream cheese sit on the counter for at least 30 minutes to make it easier to combine with the pumpkin.