1. Set the oven rack to the middle position and preheat the oven to 350 degrees Fahrenheit.
2. To make the crust, rub all the crumble ingredients with your fingers in a large bowl until the mixture resembles the consistency of wet sand. Press half or slightly more than half of the crumble into the bottom and about one-and-a-half inches up the sides of a deep nine-inch square pan. A glass pan (like Pyrex) or a dark metal pan will give you a crisper crust.
3. To make the filling, process all the filling ingredients in a food processor until smooth. Pour the filling into the crust. Sprinkle the remaining crumbs evenly over the filling.
4. Bake for 45 minutes to one hour until the filling is set around the edges but still jiggly in the middle. Cool the pie completely to allow the filling to set before slicing.
To roast the pumpkin, slice it in half, scoop out the seeds (which you can also roast and eat), and place the halves face down on a baking sheet. Bake in a preheated, 350-degrees-Fahrenheit oven until soft and the skin starts to brown, about an hour and a half.