Preheat oven to 375° F.
In a medium mixing bowl, combine graham cracker crumbs, chopped pecans, and sugars and mix well. Stir in melted butter and salt. Press the mixture into a greased 9 inch springform pan.
Bake for 8 minutes. Remove from oven and reduce oven temperature to 350° F.
In a medium mixing bowl, whisk pumpkin puree, brown sugar, eggs, and spices.
In a separate large bowl, combine cream cheese and granulated sugar and mix well. Add cornstarch, heavy cream, and vanilla and beat until creamy. Mix pumpkin mixture into cream cheese mixture until smooth. Spoon over baked crust.
Bake at 350° for 45 minutes, then cover with foil (to prevent browning) and bake for another 15 minutes or until center is set. Remove from oven.
Prepare the sour cream topping by whisking together sour cream and granulated sugar. Spoon the mixture on top of the cheesecake and use the back of the spoon to smooth it out. Bake for an additional 10 minutes.
Place baked cheesecake on a cooling rack and cool completely, then transfer to the refrigerator for 8-10 hours before serving.