Preheat oven to 350 degrees.
In a large mixing bowl mix egg, oil, and sugar together. Add vanilla and zucchini.
In a separate bowl add flour, cocoa, salt, soda, and cocoa. Stir.
Add dry ingredients to wet ingredients. Stir to until combined.
Spread batter, it will be thick, in a greased jelly roll pan.
Bake for 18-20 minutes.
Boil butter, cocoa, and milk in a medium saucepan.
Remove from heat and add vanilla, salt, and powdered sugar. Stir until smooth. I usually use a whisk. Frost brownies while they are still warm.
Sprinkle Butterfinger pieces over icing.