Preheat oven to 375 degrees.
To a large bowl, add the pumpkin puree, evaporated milk, and eggs and mix.
In a second bowl, mix sugar, light brown sugar, dark brown sugar, flour, cinnamon, nutmeg, salt, and ginger.
Add the sugar spice mixture to the pumpkin mixture.
If you are using homemade pie crust add it to the bottom of the pie pan.
Add the pumpkin mixture to the pie crust.
Combine the dark brown sugar, old fashioned oats, chopped pecans, flour, butter, cinnamon, and nutmeg with a fork until a crumble forms.
Add the pecan streusel evenly over the pie filling.
Bake for 60-70 minutes until the middle of the pie is no longer jiggly when touched.
Cool pie for 2 hours before serving so the filling completely sets.
