Preheat the oven to 350°F (180°C). Melt the vegan butter in the microwave for 30-40 seconds or on the stovetop. Take the plant milk and vegan yogurt out of the refrigerator so they can start to come to room temperature.
Grease a 9x5 loaf pan. Or, you can line it with parchment paper to make it easier to pull out of the dish. Make the vegan buttermilk by stirring the apple cider vinegar into the plant milk.
Combine the flour, cane sugar, cocoa powder, cornstarch, baking powder, and salt in a medium-sized bowl. I like to use a sifter here to break up any clumps.
Add the vegan buttermilk, yogurt, melted butter, and vanilla to a large bowl. Whisk them together until it's smooth and creamy.
Add the dry ingredients to the wet ingredient bowl and stir them together just until you only see a few streaks of flour left. Fold in most of the chocolate chips, saving some for toppings.
Pour the batter into the prepared loaf pan. Smooth it out with the back of a spoon and top it with the remaining chocolate chips.
Bake the bread for 55-60 minutes or until a toothpick comes out mostly clean. A few moist crumbs are okay. Check a couple of different spots near the center in case your toothpick runs through a melted chocolate chip.
Let the bread cool for 15 minutes in the loaf pan. Then remove it and let it cool for another 15 minutes on a wire rack before slicing it.