Preheat oven to 425.
In a large bowl, whisk together pure pumpkin, sugar and evaporated milk.
Crack in eggs, one at a time, and sprinkle in pie spice and cinnamon. Whisk to combine.
Pour into lightly sprayed round baking dish.
Bake at 425 for 15 minutes. Turn heat down to 350 and bake 20 more minutes.
While pumpkin filling is baking, make streusel topping: use a pastry cutter to cut together butter, brown sugar, cinnamon and flour until the mixture is full of pea-size pieces.
Stir in dried cranberries and walnuts.
When the timer goes off, remove pumpkin filling from the oven. Sprinkle streusel over the top to cover.
Place pumpkin crumble back in oven and continue baking 25 minutes or until a knife inserted near the center comes out clean.