Streusel:

1. In a medium bowl stir together the sugars, cinnamon, salt, and melted butter and flour until well combined. Set aside. (Mixture should look like wet sand with big and small chunks)

For the cake:

1. Preheat your oven to 350 degrees F. Grease a 9×13 inch glass baking dish with nonstick spray or rub with butter.
2. In a medium bowl combine the eggs, 1 cup of the sour cream and the vanilla.
3. Using a stand mixer fitted with the paddle attachment, mix flour, sugar, baking powder, baking soda and salt on low speed for about 30 seconds.
4. Add the 12 tablespoons butter and the remaining ½ cup remaining sour cream and mix on low until dry ingredients are moistened, about 1 1/2 minutes. Increase the speed to medium and mix until batter comes together, about 20 to 30 seconds. Lower the speed to medium-low and slowly add the egg and sour cream mixture, in 3 additions, beating for 20 seconds and scraping the bowl after each addition. Increase the speed to medium-high and beat until the batter is light and fluffy, about 1 more minute.
5. Spread 2 cups of batter into the bottom of your prepared  pan. Sprinkle about 1 1/4 cups of streusel evenly over the top. Spread another 2 cups of the batter on top and spread it around as best you can. Sprinkle with another 1/14 cups of the streusel.
6. Spread the remaining batter on top as evenly as you can and finish off with the remaining streusel (I know it might seem like a lot, but trust me it’s going to be amazing!).
7. Bake 50 to 60 minutes, or until the cake feels firm to the touch and a skewer inserted in the center comes out clean.  Let the cake cool on a wire rack for about 10-12 minutes before drizzling with icing.

Icing:

1. In a medium bowl, combine the butter, powdered sugar, vanilla, salt and half & half. Whisk together until smooth. Drizzle over the top of the warm coffee cake.