Preheat oven to 350 degrees. Spray 9 x 13 pan with non-stick spray and set aside.

Make the streusel by whisking together flour, brown sugar, sugar, salt, cinnamon, and pumpkin spice in a large bowl.

Melt butter in the microwave. Pour into the dry ingredients and mix until you have wet, big chunks. Refrigerate until ready to use.

Make the cake batter by whisking together flour, sugar, baking powder, baking soda, salt, pumpkin pie spice, and cinnamon in a large bowl.

Cut butter into chunks. Add to the flour mixture.

Add 1/2 can pumpkin puree to the mixture and beat until it comes together in a ball.

In a separate bowl, add remaining pumpkin puree. Whisk in eggs, oil, and vanilla until well combined.

Add the egg mixture to the flour mixture in 3 additions, beating between each one.

Spread 2 cups of batter evenly into the bottom of the pan.

Sprinkle 1 cup streusel evenly over the top.

Spread another 2 cups batter on top and spread the best you can.

Add another 1 cup streusel on top.

Add the rest of the batter and spread evenly.

Evenly spread another 2 cups of streusel on top of the cake. Set remaining aside.

Bake for 35 minutes.

Remove from the oven and quickly sprinkle remaining streusel evenly over the top.

Bake for another 10 minutes.

Let the cake cool for 15-20 minutes.

Make the icing by beating together softened butter, vanilla, salt, milk, and powdered sugar in a medium size bowl until smooth.

Drizzle about half the icing over the cake. Then drizzle each slice with additional icing before serving.