Pour the chilled heavy cream into a large bowl and whip it with a hand mixer for 3 to 4 minutes, or until stiff peaks form.
In another bowl, add the pumpkin puree and evaporated milk. Mix well with a whisk.
Add the instant vanilla pudding mix, Greek yogurt, pumpkin pie spice and vanilla extract. Whisk until everything is well combined.
Add the whipped cream to the pumpkin mixture and gently fold everything together. Be careful not to overmix. Refrigerate for an hour.
Use an ice cream scoop to divide the mousse between serving glasses.
Top with a little whipped cream. Finish with a sprinkle of ground cinnamon.