Preheat oven to 325 and spray a donut pan with cooking spray. * We doubled this recipe to make 12 donuts (2 pans). In a small bowl, prepare the topping by melting the butter and adding in the brown sugar, flour, and cinnamon.
Combine with a fork until crumbs form and set aside.
In a different bowl, sift together the flour, baking powder, cinnamon, and salt. Set aside.
In a mixing bowl, cream together the sugar, egg, and butter.
Add in the milk and vanilla.
Slowly add in the dry ingredients until all is combined.
Pour batter into a Ziploc bag for easier pouring.
Cut end off bag and pipe batter into sprayed donut pan.
Divide crumb topping evenly between each donut and sprinkle on top.
Place pan in preheated oven for about 15-17 minutes.
Remove from oven and allow to cool for a few minutes before removing from pan.
Make glaze while waiting for donuts to cool slightly.
Combine the powdered sugar, vanilla, and milk in a small bowl.
Drizzle on top of each donut. Serve!!