Begin by whipping the cream to soft peaks. The optional addition of the cream of tartar at this point helps the cream maintain form. Set cream aside.
In a clean bowl, on low speed, begin to whip the mascarpone. Then, slowly incorporate the sugar (high speed causes sugar to fly all over).
Once the mascarpone and sugar are mixed, add the pumpkin puree and the cinnamon, ginger, nutmeg and cloves. Mix thoroughly to completly combine all ingredients.
Fold all of the cream into the pumpkin-mascarpone mixture, being careful not to over-mix which will cause you to loose the air in the whipped cream. Set aside.
In a bowl, mix the coffee and rum. Briefly dip each lady finger in the coffee mixture (too much coffee will cause you to have a soggy dessert). Place the moistened cookies in the trifle bowl (or serving dish of your choice), lining the bottom. Once you have one layer of cookies in place, cover them with about 1/3 of the pumpkin mixture.
Continue layering moistened lady fingers and pumpkin mixture. Depending on the size of your serving dish, you may have some pumpkin mixture left over.
Cover the completed dish with plastic wrap and let set-up in the fridge for several hours or overnight. With time, the flavors will meld.
Place a light dusting of cinnamon on top just before serving/presenting.