Place the pumpkin halves in a large saucepan, and fill with water to barely cover. Bring the pan to a boil, then reduce heat to medium-low and simmer the pumpkin until tender, about 30 minutes. Drain the pumpkin and scoop out the pumpkin meat; discard the peel. Mash the pumpkin until smooth.
Preheat an oven to 400 degrees F (200 degrees C).
Place 2 cups of the mashed pumpkin in a large bowl, and stir in the milk, coffee creamer, eggs, brown sugar, walnuts, and cinnamon until the mixture is well combined. Spoon the filling into the pie crust, and bake in the preheated oven until the pie filling is firm and cooked through, about 1 hour.