Combine cream and sugar in a saucepan over medium heat: stir until sugar is dissolved. Whisk in pumpkin until well blended; add pumpkin pie spice and vanilla. Simmer for 10 min, or until mixture is warm. Pour into mugs and serve with a dollop of whipped cream and a sprinkle of pumpkin pie spice.
If you are going to dip your mug into graham cracker crumbs do so right before pouring the drink into the mug(s). The recipe can easily be halved for an individual serving.