Preheat oven to 350°F. Line a 9-by-13 inch baking pan with parchment and grease with non-stick spray.
In a medium bowl, whisk flour, cinnamon, ginger, baking soda and salt; set aside.
Cream butter and sugar together until light and airy. Beat in egg and vanilla until combined. Add pumpkin puree and beat.
Mix in dry ingredients until just combined. *Mixture will be thick, that’s okay!
Fold in white chocolate and spread batter evenly in pan.
Make streusel topping: whisk together dry streusel ingredients. Work in butter until a coarse crumb forms.
Sprinkle streusel on top of batter and bake for 35-40 minutes.
Allow to cool completely before removing from pan.