Preheat your oven to 350°F (175°C) and grease a 9x13 inch cake pan.

In a medium bowl, whisk together all-purpose flour, brown sugar, granulated sugar, cinnamon, and salt. Pour in melted butter and mix until it resembles wet sand.

In a large bowl, whisk together all-purpose flour, granulated sugar, kosher salt, cinnamon, and pumpkin pie spice until well-blended.

Mix softened butter into the dry ingredients until crumbly. Then add canned pumpkin puree and stir until incorporated. In a separate bowl, whisk together eggs, vegetable oil, and vanilla extract. Combine this with the batter until just blended.

Spoon 2 cups of the cake batter into the prepared pan, then sprinkle 1 cup of the streusel topping over it. Repeat the layering process, finishing with streusel on top.

Bake for 35 minutes, then add the remaining streusel on top and bake for another 10-15 minutes. Check for doneness with a toothpick.

Let the cake cool in the pan for at least 15 minutes. Prepare the glaze by mixing powdered sugar, milk, and melted butter until smooth. Drizzle over the cooled cake.