This recipe is based on a recipe from King Arthur (the flour company, not His Highness, LOL!) I've modified the recipe to our liking and it is fantastic! It is super chocolatey, super moist, and you'd never guess that there is zucchini in it. What a great way to eat our veggies!
Preheat oven to 350°F. Lightly grease a 9" x 13" pan.
In a medium bowl, mix together flour, baking soda, baking powder and salt; set aside.
In a small bowl, mix together the cocoa and espresso powder; set aside.
In a large mixing bowl, beat butter until creamy; add sugar; beat until creamy.
Add oil and vanilla; beat until smooth.
Add eggs; beat well.
Stir in 1/3 of the flour mixture; stir in 1/2 the sour cream; stir in 1/2 of remaining flour mixture; stir in rest of sour cream; add remainder of flour mixture and cocoa & espresso powder mixture; stir to mix thoroughly.
Stir in zucchini and 1/2 cup chocolate chips.
Pour into prepared pan, smoothing to level batter.
Bake at 350ºF for 35-40 minutes, until center springs back when lightly touched and cake appears set. (Note: Time is approximate due to type of pan and oven variations.)
Remove cake from oven, sprinkle fairly evenly with 1/2 cup chocolate chips, and return it to oven for 8-10 minutes, or until toothpick inserted in center comes out almost clean.
Remove cake from oven; use an off-set spatula or dinner knife to spread the chocolate chips into a smooth glaze. Set pan on a wire rack and let cool completely (about 2 hrs.)
When cooled, use knife or small off-set spatula to spread frosting evenly over cake.
Note: You may use your favorite ganache instead of melted chocolate chip glaze and frosting, if preferred.