Preheat your oven to 350 degrees. Grease and flour a 9 inch spring form pan or deep dish cake pan. Set aside.

In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, ginger, salt, and nutmeg.

In the bowl of a stand mixer or a large bowl with a hand mixer, cream together the butter and brown sugar. Add in the eggs, pumpkin, and sour cream and mix until fully combined.

Slowly mix in the flour mixture.

In another bowl, combine the dry streusel ingredients: flour, brown sugar, cinnamon, and salt.

Using a fork, mix in the cold butter pieces until it forms pea sized crumbles.

Spread half of the cake batter into the cake pan, followed by half of the streusel. Repeat.

Bake in the preheated oven for 50 minutes.

Allow to fully cool.

To make the Icing: Whisk together the powdered sugar, milk, and vanilla extract until it turns into a smooth glaze. Drizzle over the cooled cake and serve.