CINNAMON CRUMBLE TOPPING
Preheat oven to 350 degrees F. Spray a donut pan with non stick cooking spray.
In a large mixing bowl, sift together all-purpose flour, cornstarch, baking powder, cinnamon, sugar, and salt. Set aside.
In a small bowl, whisk together buttermilk*, egg, and melted butter.
For filling the donut pan, use a pastry bag or a Ziploc bag with the corner cut to pipe the batter into the pan. Fill the donuts about 2/3 full or until all batter is used.
Bake in the oven for 7-9 minutes or until stop of donuts are puffy and appear dry. Remove from oven and allow to rest for 2 minutes in the donut pan, then transfer to a wire cooling rack to cool completely.
In a small bowl, whisk together milk, sugar, and vanilla. Pour icing into a pastry bag with a small tip or in a Ziploc bag with the corner cut out. Set aside.