Preheat the oven to 325˚F. Line a rimmed baking sheet with aluminum foil.

In the bowl of a food processor, add graham crackers and process until fine crumbs. Add sugar, melted butter, and cinnamon for crumble, then pulse until the mixture comes together to form small nuggets.

Dump the mixture onto the prepared baking sheet and bake for 10 minutes, until light golden brown. Set aside to cool completely.

Add cream cheese, confectioners' sugar, vanilla extract, and pumpkin pie spice to the bowl of a stand mixer fitted with the paddle attachment. Beat until fluffy, about 3 to 5 minutes. Beat in pumpkin puree until incorporated. Gently fold in whipped cream with a spatula.

Divide the crumble among 6 dessert dishes. Top with equal amounts of the mousse, spreading the top with the back of a spoon to even out. You can also pipe the mixture into the dishes if you prefer.

Cover and refrigerate for at least 2 hours and up to 2 days.