Spray a 24 count mini muffin pan with non-stick cooking spray and set aside.
In medium bowl, mix together your flour, baking powder, salt and sugar until combined.
Add in your egg, sour cream, milk, butter and vanilla and stir until blended.
Add your batter to a piping bag or a ziploc bag with the tip cut off and pipe muffin cups about 1/2 full of batter.
Bake for about 10 minutes or until lightly golden, remove from oven and let cool.
Meanwhile on stove in saucepan melt your butter, remove from heat and stir in your cocoa powder, vanilla and milk until combined.
Slowly whisk in your powdered sugar until there is no lumps.
Add your crushed Butterfingers to a small bowl.
Dip each of your donut holes into glaze then shake in crushed Butterfingers.
Let set for about 10-15 minutes to harden up.