Preheat the oven to 350 degrees
Line a pie plate with the pie crust
Fold and crimp the edges over
In a large bowl, mix the gingersnaps, pecans, powdered sugar, and 1/4 cup of melted butter
Add only 2 cups of the gingersnap mixture to the pie crust - spreading out to cover the edges and bottom
In a separate large bowl, Mix the pumpkin puree, milk, eggs, sour cream, extract, and ginger
Pour the pumpkin mixture over the gingersnap mixture
Bake for 30 minutes
In a medium-sized bowl, add the leftover gingersnap mixture to the flour, brown sugar, and 2 Tbsp. of melted butter - mix together until it is crumbly
Add the Streusel (gingersnap and pecan) mixture to the edges of the pumpkin pie (or to the center leaving the edges alone), and bake for another 40-45 minutes - or until the pie has set
If the crust is getting too brown, cover the crust with aluminum foil for the last 30 minutes
Optional toppings - whipped topping and cinnamon