Whisk together the pumpkin puree, sugar, cinnamon, pumpkin pie spice and heavy cream in a medium saucepan.
Cook the mixture over medium heat until it's hot but not bubbling. Be sure to whisk it often.
In a small bowl whisk the eggs and cornstarch together.
Add the egg mixture to the saucepan whisking constantly.
Continue cooking until the mixture is thick and bubbling. Be sure to stir constantly!
Let filling cool completely before pouring it over your cooled crust.
Chill the tart at least one hour before serving.