Preheat oven to 350F.
In a food processor, finely grind the gingersnaps. Mix in the melted butter until moist and crumbly. Pour into a tart pan with a removable bottom, press into pan.
Bake crust for 10-12 minutes. Remove from oven; allow to cool slightly.
In a bowl, whisk together milk, yolks and pumpkin until smooth. Pour into prepared crust.
Bake for 30 minutes, or until set and beginning to brown on top.
Remove from oven and allow to cool for at least one hour.
Top with fresh whipped cream and cranberries, if desired.