In the same mixing bowl, add the flour and salt and mix until combined ... In a small bowl, make the streusel topping by whisking together the brown sugar and flour. Chop the butter into small pieces ...
If you're familiar with what streusel is and why it works as a coffee cake topping ... use cold butter or melted butter, and you'll want to start with about 4 to 6 tablespoons per 2 cups of mix ...