In the bowl of a stand mixer fitted with the whisk attachment, beat 1½ cups of heavy cream along with the maple syrup and vanilla on medium speed until stiff peaks form, about 2 minutes.
2 cups heavy cream, ¼ cup pure maple syrup, 1 teaspoon pure vanilla extract
Remove the mixture to a bowl and place it in the refrigerator while you make the pudding base.
Add the pumpkin puree, cream cheese, and pumpkin pie spice to the bowl of a stand mixer fitted with the paddle attachment and beat them together until combined, about 1 minute.
1½ cups pumpkin puree, 4 ounces cream cheese, 1 teaspoon pumpkin pie spice
With the mixer on low, slowly add the milk and the remaining ½ cup of heavy cream. Mix until combined.
1 cup whole milk
Add the pudding mix and whisk on medium speed until the mixture is well combined and thickened slightly, about 2 minutes.
3.4 ounces vanilla pudding mix
Gently fold the whipped cream mixture into the pudding mixture.
Spoon or pipe the mousse into serving containers. Chill for at least 2 hours before serving.
Garnish with crumbled gingersnaps or graham crackers.