Preheat your oven to 350°F and line or grease 10-inch bundt pan.
Add sugar and softened butter to a large mixing bowl. Use a hand mixer on high to combine until smooth. ¾ cup granulated sugar, ½ cup unsalted butter, softened
Add zest, eggs, and vanilla and combine with hand mixer on low.
4 to 5 tablespoons orange zest, 3 large eggs, 1 teaspoon vanilla extract
With mixer still on low, add flour, cocoa powder, baking powder, baking soda, salt, and orange juice. Mix until smooth.
1 cup all-purpose flour, ¾ cup cocoa powder, 1 ½ teaspoon baking powder, ¼ teaspoon baking soda, ¼ teaspoon salt, 1 cup orange juice
Transfer batter to your greased bundt pan and bake for 25-30 minutes, until a toothpick comes out clean.