Preheat oven to 350 degrees.  

Process 3 cups pecans (in a food processor or blender) until ground up. Transfer to a medium-size bowl. 

Add melted butter and sugar to the pecans and stir to combine. 

Prepare a 10 ½ inch springform pan with non-stick cooking spray or greasing with shortening. Pat pecan mixture into the bottom of the pan. Freeze for 10 minutes while preparing next layer. 

In a large mixing bowl, mix the softened cream cheese with the sugar. Add in the eggs one at a time, mixing in between. Mix in the vanilla. 

Pour the cream cheese mixture over the pecan crust, and spread out evenly. 

Freeze for 20 minutes. 

In a large mixing bowl, combine the pumpkin pie ingredients and mix until nicely incorporated. Pour over the partially frozen cheesecake filling. 

Bake for 40-45 minutes until the pumpkin pie is starting to firm up around the outside. 

Mix the streusel topping ingredients in a small bowl and then drop in spoonfuls over the partially baked pie. 

Return the pie to the oven, and bake for an additional 50-65 minutes, or until the pumpkin and pecan topping is set.