While pie shell is baking, whisk cream, milk, eggs, yolks and vanilla together in medium bowl. Combine pumpkin puree, yams, sugar, maple syrup, ginger, cinnamon, nutmeg and salt in large heavy-bottomed saucepan; bring to sputtering simmer over medium heat, 5 to 7 minutes. Continue to simmer pumpkin mixture, stirring constantly and mashing yams against sides of pot, until thick and shiny, 10 to 15 minutes.
Remove pan from heat. Whisk in cream mixture slowly, until fully incorporated.
Strain mixture through fine-mesh strainer set over medium bowl, using back of ladle or spatula to press solids through strainer. Re-whisk mixture and transfer to warm pre-baked pie shell.
Return pie plate with baking sheet to oven and bake pie for 10 minutes.
Reduce heat to 300 degrees. Continue baking until edges are set (instant-read thermometer inserted in center registers 175 degrees), 20 to 35 minutes longer.
Transfer pie to wire rack and cool to room temperature, 2 to 3 hours. (The pie finishes cooking with resident heat; to ensure the filling sets, cool it at room temperature and not in the refrigerator.)