Grease a donut pan with cooking spray.

In a large bowl, add the Flour, Sugar, Cinnamon, Baking Powder, and Salt, and blend with the Whisk attachment.

In a separate bowl, add the Milk, Eggs, and Vanilla Extract, and stir or Whisk together until well blended.

Add the Shortening to the mixing bowl, and mix the egg mixture until blended.

Pour the wet ingredients into the dry ingredients and stir until just combined.

Using a piping bag or a spoon, fill the prepared donut pan with the doughnut batter, about ⅔ full.

To make the streusel topping, combine the brown sugar, flour, and cinnamon in a medium bowl.

Add the melted butter and mix until the mixture resembles coarse crumbs.

Sprinkle the streusel topping evenly over the donut batter.

Bake for 10-11 minutes or until a toothpick inserted into the center of a donut comes out clean and the donuts are golden brown.

Allow the donuts to cool in the pan for a few minutes before transferring them to a wire rack to cool completely.

To make the sweet glaze, add the Powdered Sugar, and Milk in a small bowl, and stir well until blended.

When the doughnuts are cool, drizzle the glaze on top of the donuts.