1. Preheat the oven to 325°F and lightly grease a 9-inch springform pan.

2. Mix the graham cracker crumbs, 1/4 cup brown sugar, and 6 tablespoons melted butter until evenly combined. Press into the bottom of the pan and bake for 8 to 10 minutes. Let cool slightly.

3. Beat the cream cheese until smooth. Add the granulated sugar and mix until creamy.

4. Add the pumpkin puree, sour cream, vanilla extract, 1 1/2 teaspoons cinnamon, nutmeg, ginger, and salt. Mix until smooth.

5. Add the eggs one at a time, mixing on low speed just until combined.

6. Pour the filling over the crust and smooth the top.

7. In a separate bowl, stir together the flour, 1/2 cup brown sugar, 1 teaspoon cinnamon, 5 tablespoons melted butter, and chopped pecans until crumbly.

8. Sprinkle the streusel evenly over the cheesecake.

9. Bake for 60 to 70 minutes, until the edges are set and the center still has a slight wobble.

10. Turn off the oven, crack the door open, and let the cheesecake rest inside for 1 hour.

11. Cool completely at room temperature, then refrigerate for at least 6 hours or overnight.

12. Slice and serve with whipped cream.