Preheat the oven to 350 degrees Fahrenheit. Prepare a baking dish with parchment paper and set aside.

In a mixing bowl, sift the flour, cake flour, baking powder and soda, salt and sugar together.

Then add the butter, vegetable oil, sour cream, vanilla extract, eggs buttermilk, and milk. Whisk this together until combined and a batter forms.

Set this aside, and make the streusel. In a separate medium sized bowl, add the flour, brown sugar, cinnamon and salt. Blend together with a fork..

Then add the butter in cubes and use the fork to press into the mixture, until a crumbly streusel forms.

Take the prepared baking dish and pour half of the cake batter into it. Coat that layer with a heavy amount of streusel.

Then top with the rest of the cake batter and coat again with the rest of the streusel.

Bake in the oven for 35-40 minutes, or until a toothpick inserted comes out clean.

While this cools, make the glaze.

In a small bowl, add the powdered sugar and milk. Whisk together until a thin glaze forms.

Remove the coffee cake from the baking dish with the parchment paper and drizzle with the glaze.

Cut, serve and enjoy!