Chocolate Zucchini Muffins

2 cups all purpose flour
1 cup cocoa, sifted
1/2 teaspoon salt
2 teaspoon baking soda
1 1/2 cups brown sugar
3/4 cup vegetable oil
3 eggs
1 teaspoon vanilla
1/2 cup buttermilk
2 cups zucchini, washed and dried, ends and stems removed, cut in half lengthwise and seeded,and grated
1 cup semi-sweet chocolate chips

Preheat oven to 350 degrees F. Line 20 muffin cups with muffin liners or spray with nonstick cooking spray.
In a large bowl whisk together flour, cocoa, salt, baking soda and cinnamon; set aside.
In a medium bowl whisk together the sugar, butter and oil. Beat in eggs, one at a time until combined. Stir in vanilla, buttermilk, zucchini and chocolate chips. Gently stir the liquid ingredients into the dry ingredients until just combined.
Divide batter equally among prepared muffin cups. Bake until toothpick inserted into the center comes out clean and muffin tops are springy to the touch, 20 to 24 minutes; rotating halfway through baking time. Cool muffins in muffin tin for 5 minutes, then transfer to wire rack and cool 5 minutes before serving.