Preheat the oven to 350°F. Spray a 9 x 13" pan with nonstick cooking spray. Set aside. In the bowl of a stand mixer add the flour, sugar, brown sugar, baking powder, baking soda, pumpkin spice, cinnamon, and salt. Whisk to combine.
Add the egg, milk, pumpkin puree, and vanilla. Using the paddle attachment on medium low speed, mix until the wet ingredients are incorporated.
Using a spatula, spread the batter into the prepared pan.
Combine the streusel ingredients into a medium size bowl. Using your hands, mix until the butter resembles the size of peas. Evenly distribute the streusel mixture over the cake batter. Bake for 22-25 minutes. The cake is done when a toothpick is inserted into the center and it comes out clean, or with a few moist crumbs on it. Let the cake cool as you prepare the glaze.
Prepare the glaze by whisking the glaze ingredients. Using a spoon, carefully drizzle the glaze over the cake. Serve immediately.