Preheat oven to 350°F. Grease a 13x9-inch baking dish or line with parchment paper.
For the cake, in a medium bowl, whisk together flour, sugar, brown sugar, baking powder, baking soda, salt, cinnamon, and pumpkin pie spice.
In a separate large bowl, whisk together butter, eggs, vanilla extract, sour cream, and pumpkin puree until smooth.
Pour the dry ingredients into the wet, and stir until just combined.
For the streusel, in a small bowl, mix together flour, brown sugar, pumpkin pie spice, and salt. Add butter and mix with a fork or with your fingers until the mixture resembles coarse crumbs.
Pour the cake batter into the prepared baking dish, spreading it evenly. Sprinkle the streusel topping evenly over the batter. Using a butter knife, pierce the streusel into the cake batter 10-15 times.
Bake 45-55 minutes or until a toothpick inserted into the center comes out with a few moist crumbs.
For the icing, in a small bowl, whisk together powdered sugar, maple syrup, milk and vanilla extract. Add more milk for a thinner consistency, if desired.
Let the coffee cake cool in the pan for at least 10 minutes. Drizzle the icing over the cooled cake.