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 grease with shortening. Pat pecan mixture into the bottom of the pan. Freeze for 10minutes while preparing the 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.

Notes: To make a graham cracker crust for the pecan crust, substitute graham cracker crumbs for the ground pecans.